[llvm] [compiler-rt] Reland "[PGO][GlobalValue][LTO]In GlobalValues::getGlobalIdentifier, use semicolon as delimiter for local-linkage varibles. " (PR #75860)

[Fangrui Song via llvm-commits]

MaskRay wrote:

> Use starts_with to replace deprecated startswith.
> Should fix the error  error: 'startswith' is deprecated: Use starts_with instead [-Werror,-Wdeprecated-declarations] in [lab.llvm.org/buildbot/#/builders/36/builds/40893](https://lab.llvm.org/buildbot/#/builders/36/builds/40893)

This echoes my [complaint](https://maskray.me/blog/2023-09-09-reflections-on-llvm-switch-to-github-pull-requests) :)

> Sometimes, only through rebasing can one notice that the patch needs adjustments to more code or tests due to its interaction with another landed patch:

I am playing with https://getcord.github.io/spr/index.html to use Phabricator workflow without affecting reviewers' experience.

https://github.com/llvm/llvm-project/pull/75860