[llvm] [IR] Allow MDString in operand bundles (PR #110805)

[Serge Pavlov via llvm-commits]

spavloff wrote:

> This commit causes a warning during build time:
> 
> ```
> C:\Users\rysza\lib\llvm-project\llvm\lib\Bitcode\Reader\BitcodeReader.cpp(801,15): warning: comparison of integers of different signs: 'unsigned int' and 'llvm::bitc::MetadataOperandBundleValueMarker' [-Wsign-compare]
>   801 |     if (ValID != bitc::OB_METADATA) {
>       |         ~~~~~ ^  ~~~~~~~~~~~~~~~~~
> ```

@R-Goc Could you please check, if https://github.com/llvm/llvm-project/pull/113428 solves this problem? 

https://github.com/llvm/llvm-project/pull/110805