[clang] [lld] [llvm] Reland "Compute GUIDs once and store in metadata" (#184065) (PR #201849)

[Mircea Trofin via cfe-commits]

mtrofin wrote:

Turns out the clang build regression was in large due to some `#include`s in the change that weren't necessary. The 30% regression when compiling `ModuleLinker goes away or reappears when either old or new compiler (i.e. pre/post this change) compiles the old or the new source.`

Fixed and [re-ran](https://llvm-compile-time-tracker.com/compare.php?from=ee890eb04639464cd523d1305c75a82628a6a8a6&to=4da2c32b603f42c823a3bfce3adb2cc64c706be8&stat=instructions:u) the compile time tracker, the largest clang-build regression is now 1%. 

https://github.com/llvm/llvm-project/pull/201849