[llvm] [BOLT] Enable cross compilation of runtime libraries (PR #101180)

[Gergely Bálint via llvm-commits]

bgergely0 wrote:

> > I realized there are already target-specific files under `lib/Target/<target>` so it felt like the right place to store the new files.
> 
> My read of this (correct me if I'm wrong) is that `lib/Target/<target>` are directories which exist in the sources. I think traditionally the install directories of library archives like this would live at `lib/<target>` rather than `lib/Target/<target>` -- sources and builds are different.

No, these exist in the build directory as well. I am following the build steps from the BOLT README, so my build dir is different from the sources.  The build/lib/Target/<target> directory contains a lot of `TableGen`erated files, and other target-specific object files.

https://github.com/llvm/llvm-project/pull/101180