Auto merge of #24902 - bombless:configure, r=pnkfelix

Closes #24840

diff --combined configure
index dbca73415fec62d11ef151ff41d2592d19d981a8,2a6d858e6af9d6c8ba0fdcf48125b09a2b8d62f0..9aebfe07967d99fc1fc268dd7649486f4fac933f
--- 1/configure
--- 2/configure
+++ b/configure
@@@ -544,14 -544,13 +544,14 @@@ f
  BOOL_OPTIONS=""
  VAL_OPTIONS=""
  
- opt debug 0 "debug mode"
+ opt debug 0 "debug mode; disables optimization unless \`--enable-optimize\` given"
  opt valgrind 0 "run tests with valgrind (memcheck by default)"
  opt helgrind 0 "run tests with helgrind instead of memcheck"
  opt valgrind-rpass 1 "run rpass-valgrind tests with valgrind"
  opt docs     1 "build standard library documentation"
  opt compiler-docs     0 "build compiler documentation"
  opt optimize-tests 1 "build tests with optimizations"
 +opt debuginfo-tests 0 "build tests with debugger metadata"
  opt libcpp 1 "build with llvm with libc++ instead of libstdc++ when using clang"
  opt llvm-assertions 0 "build LLVM with assertions"
  opt debug-assertions 0 "build with debugging assertions"
@@@ -584,7 -583,6 +584,7 @@@ valopt jemalloc-root "" "set directory 
  valopt build "${DEFAULT_BUILD}" "GNUs ./configure syntax LLVM build triple"
  valopt android-cross-path "/opt/ndk_standalone" "Android NDK standalone path"
  valopt release-channel "dev" "the name of the release channel to build"
 +valopt musl-root "/usr/local" "MUSL root installation directory"
  
  # Many of these are saved below during the "writing configuration" step
  # (others are conditionally saved).
@@@ -1060,13 -1058,6 +1060,13 @@@ d
              fi
              ;;
  
 +
 +        *-musl)
 +            if [ ! -f $CFG_MUSL_ROOT/lib/libc.a ]
 +            then
 +                err "musl libc $CFG_MUSL_ROOT/lib/libc.a not found"
 +            fi
 +            ;;
          *)
              ;;
      esac