[llvm] [CGData] Global Merge Functions (PR #112671)

[Thorsten Schütt via llvm-commits]

tschuett wrote:

Could please add one or more rst files to https://github.com/llvm/llvm-project/tree/main/llvm/docs about cgdata.
Tools, passes, flags, and more.
For better visibility.

https://github.com/llvm/llvm-project/pull/112671