[clang] Symbol names on arm64 can have an extra char on front of name (PR #194937)

[Sean Perry via cfe-commits]

perry-ca wrote:

@zeroomega I rewrote this test to use FileCheck.  I tried it with the darwin & macos targets, but can you try this again just to be sure and re-approve.  Thanks

https://github.com/llvm/llvm-project/pull/194937