Auto merge of #49558 - Zoxc:sync-misc, r=michaelwoerister

Even more thread-safety changes

r? @michaelwoerister

diff --cc src/librustc/ty/context.rs
Simple merge

diff --cc src/librustc/ty/layout.rs
Simple merge

diff --cc src/librustc/ty/maps/plumbing.rs
Simple merge

diff --cc src/librustc_metadata/encoder.rs
Simple merge

diff --cc src/librustc_trans/base.rs
Simple merge

diff --cc src/librustc_trans/debuginfo/mod.rs
Simple merge

diff --cc src/librustc_trans/llvm_util.rs
Simple merge

diff --cc src/librustc_trans_utils/lib.rs
Simple merge

diff --cc src/librustc_typeck/check/mod.rs
Simple merge

diff --cc src/librustc_typeck/lib.rs
Simple merge