Rollup merge of #56832 - alexcrichton:external-demangle, r=Mark-Simulacrum

std: Use `rustc_demangle` from crates.io

No more need to duplicate the demangling routine between crates.io and
the standard library, we can use the exact same one!

diff --combined Cargo.lock
index be4a1c2f1d3c40292b0d5530e59b38a7dcb4b231,472470de1de7e26d81b07b7fd991cfe9e85896b4..7e03474565d857a8b4af3ebc7cc48107076162b4
--- 1/Cargo.lock
--- 2/Cargo.lock
+++ b/Cargo.lock
@@@ -81,13 -81,13 +81,13 @@@ dependencies = 
  
  [[package]]
  name = "backtrace"
 -version = "0.3.9"
 +version = "0.3.11"
  source = "registry+https://github.com/rust-lang/crates.io-index"
  dependencies = [
   "backtrace-sys 0.1.24 (registry+https://github.com/rust-lang/crates.io-index)",
   "cfg-if 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
   "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
-  "rustc-demangle 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
+  "rustc-demangle 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
   "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
  ]
  
@@@ -728,7 -728,7 +728,7 @@@ name = "error-chain
  version = "0.11.0"
  source = "registry+https://github.com/rust-lang/crates.io-index"
  dependencies = [
 - "backtrace 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
 + "backtrace 0.3.11 (registry+https://github.com/rust-lang/crates.io-index)",
  ]
  
  [[package]]
@@@ -736,7 -736,7 +736,7 @@@ name = "error-chain
  version = "0.12.0"
  source = "registry+https://github.com/rust-lang/crates.io-index"
  dependencies = [
 - "backtrace 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
 + "backtrace 0.3.11 (registry+https://github.com/rust-lang/crates.io-index)",
  ]
  
  [[package]]
@@@ -751,7 -751,7 +751,7 @@@ name = "failure
  version = "0.1.3"
  source = "registry+https://github.com/rust-lang/crates.io-index"
  dependencies = [
 - "backtrace 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
 + "backtrace 0.3.11 (registry+https://github.com/rust-lang/crates.io-index)",
   "failure_derive 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  ]
  
@@@ -1813,7 -1813,7 +1813,7 @@@ name = "rand_chacha
  version = "0.1.0"
  source = "registry+https://github.com/rust-lang/crates.io-index"
  dependencies = [
-  "rand_core 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+  "rand_core 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
   "rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
  ]
  
@@@ -1835,7 -1835,7 +1835,7 @@@ name = "rand_hc
  version = "0.1.0"
  source = "registry+https://github.com/rust-lang/crates.io-index"
  dependencies = [
-  "rand_core 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+  "rand_core 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  ]
  
  [[package]]
@@@ -1860,7 -1860,7 +1860,7 @@@ name = "rand_xorshift
  version = "0.1.0"
  source = "registry+https://github.com/rust-lang/crates.io-index"
  dependencies = [
-  "rand_core 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+  "rand_core 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  ]
  
  [[package]]
@@@ -2060,7 -2060,7 +2060,7 @@@ name = "rustc
  version = "0.0.0"
  dependencies = [
   "arena 0.0.0",
 - "backtrace 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
 + "backtrace 0.3.11 (registry+https://github.com/rust-lang/crates.io-index)",
   "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
   "byteorder 1.2.7 (registry+https://github.com/rust-lang/crates.io-index)",
   "chalk-engine 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@@ -2195,8 -2195,12 +2195,12 @@@ dependencies = 
  
  [[package]]
  name = "rustc-demangle"
- version = "0.1.9"
+ version = "0.1.10"
  source = "registry+https://github.com/rust-lang/crates.io-index"
+ dependencies = [
+  "compiler_builtins 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
+  "rustc-std-workspace-core 1.0.0",
+ ]
  
  [[package]]
  name = "rustc-hash"
@@@ -2315,7 -2319,7 +2319,7 @@@ dependencies = 
   "cc 1.0.25 (registry+https://github.com/rust-lang/crates.io-index)",
   "memmap 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)",
   "num_cpus 1.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
-  "rustc-demangle 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
+  "rustc-demangle 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
   "rustc_llvm 0.0.0",
  ]
  
@@@ -2331,7 -2335,7 +2335,7 @@@ dependencies = 
   "memmap 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)",
   "num_cpus 1.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
   "rustc 0.0.0",
-  "rustc-demangle 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
+  "rustc-demangle 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
   "rustc_allocator 0.0.0",
   "rustc_apfloat 0.0.0",
   "rustc_codegen_utils 0.0.0",
@@@ -2892,6 -2896,7 +2896,7 @@@ dependencies = 
   "panic_unwind 0.0.0",
   "profiler_builtins 0.0.0",
   "rand 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)",
+  "rustc-demangle 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
   "rustc_asan 0.0.0",
   "rustc_lsan 0.0.0",
   "rustc_msan 0.0.0",
@@@ -3380,7 -3385,7 +3385,7 @@@ source = "registry+https://github.com/r
  "checksum arrayvec 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)" = "a1e964f9e24d588183fcb43503abda40d288c8657dfc27311516ce2f05675aef"
  "checksum assert_cli 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)" = "98589b0e465a6c510d95fceebd365bb79bedece7f6e18a480897f2015f85ec51"
  "checksum atty 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "9a7d5b8723950951411ee34d271d99dddcc2035a16ab25310ea2c8cfd4369652"
 -"checksum backtrace 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)" = "89a47830402e9981c5c41223151efcced65a0510c13097c769cede7efb34782a"
 +"checksum backtrace 0.3.11 (registry+https://github.com/rust-lang/crates.io-index)" = "18b65ea1161bfb2dd6da6fade5edd4dbd08fba85012123dd333d2fd1b90b2782"
  "checksum backtrace-sys 0.1.24 (registry+https://github.com/rust-lang/crates.io-index)" = "c66d56ac8dabd07f6aacdaf633f4b8262f5b3601a810a0dcddffd5c22c69daa0"
  "checksum bit-set 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "6f1efcc46c18245a69c38fcc5cc650f16d3a59d034f3106e9ed63748f695730a"
  "checksum bit-vec 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "4440d5cb623bb7390ae27fec0bb6c61111969860f8e3ae198bfa0663645e67cf"
@@@ -3578,7 -3583,7 +3583,7 @@@
  "checksum rustc-ap-serialize 306.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "5b2c0e8161e956647592a737074736e6ce05ea36b70c770ea8cca3eb9cb33737"
  "checksum rustc-ap-syntax 306.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1adc189e5e4500a4167b9afa04e67067f40d0039e0e05870c977bebb561f065a"
  "checksum rustc-ap-syntax_pos 306.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "4d42c430dbb0be4377bfe6aa5099074c63ac8796b24098562c2e2154aecc5652"
- "checksum rustc-demangle 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)" = "bcfe5b13211b4d78e5c2cadfebd7769197d95c639c35a50057eb4c05de811395"
+ "checksum rustc-demangle 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)" = "82ae957aa1b3055d8e086486723c0ccd3d7b8fa190ae8fa2e35543b6171c810e"
  "checksum rustc-hash 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "7540fc8b0c49f096ee9c961cda096467dce8084bec6bdca2fc83895fd9b28cb8"
  "checksum rustc-rayon 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "8c6d5a683c6ba4ed37959097e88d71c9e8e26659a3cb5be8b389078e7ad45306"
  "checksum rustc-rayon-core 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "40f06724db71e18d68b3b946fdf890ca8c921d9edccc1404fdfdb537b0d12649"