[clang] [compiler-rt] [llvm] [sancov] Add -fsanitize-coverage=trace-args,trace-ret (PR #201410)

[Marco Elver via cfe-commits]

================
@@ -0,0 +1,745 @@
+=================
----------------
melver wrote:

Something is wrong with this PR - this file already exists in the repo, though I think it was renamed to clang/docs/SanitizerCoverage.md. 

Can you please rebase the patchset so we can review?

https://github.com/llvm/llvm-project/pull/201410