[SanitizerCoverage] Add associated metadata to pc-tables.
Summary:
Using associated metadata rather than llvm.used allows linkers to
perform dead stripping with -fsanitize-coverage=pc-table. Unfortunately
in my local tests, LLD was the only linker that made use of this metadata.
Partially addresses https://bugs.llvm.org/show_bug.cgi?id=34636 and fixes
https://github.com/google/sanitizers/issues/971.
Reviewers: eugenis
Reviewed By: eugenis
Subscribers: Dor1s, hiraditya, llvm-commits, kcc
Differential Revision: https://reviews.llvm.org/D48203
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@334858
91177308-0d34-0410-b5e6-
96231b3b80d8