[Chapel Merge] Add a `bundled` target to the llvm Makefile

Branch: refs/heads/master
Revision: ac71573
Author: daviditen
Log Message:

Merge pull request #16735 from daviditen/llvm-bundled

Add a bundled target to the llvm Makefile

[reviewed by @ben-albrecht]

The llvm build expects to have a target matching what CHPL_LLVM is set to,
so add a bundled target that just requires the llvm target. This should fix the
llvm nightly testing errors.

Modified Files:
M third-party/llvm/Makefile

Compare: https://github.com/chapel-lang/chapel/compare/b9e414b3dd78...ac71573dee6f