[Chapel Merge] Enable linking with LLVM by default

Branch: refs/heads/master
Revision: 8770c06
Author: daviditen
Log Message:

Merge pull request #17133 from daviditen/llvm-enabled

Enable linking with LLVM by default

[reviewed by @mppf]

If CHPL_LLVM is set to a valid value, do what it requests. Otherwise, if the
bundled LLVM is already built, use it. Otherwise, if there is a system LLVM,
use it. Otherwise, issue an error requesting that the user set CHPL_LLVM
to a valid value.

Signed-off-by: David Iten daviditen@users.noreply.github.com

Modified Files:
M third-party/llvm/Makefile

M util/chplenv/chpl_llvm.py

Compare: https://github.com/chapel-lang/chapel/compare/976dd2c85b05...8770c0675b23