Merge pull request #16686 from gbtitus/dup-e5584b1
Improve CHPL_LIBFABRIC handling.
(Duplicate PR #16605 from master to 1.23-for-EX.)
(Original PR reviewed by @ronawho.)
Make a couple of adjustments to the CHPL_LIBFABRIC handling. The main
change is to default to CHPL_LIBFABRIC=system whenever pkg-config exists
and can find a libfabric, on the assumption that a system one is more
likely to match up with the system’s characteristics than our bundled
one is. While here, also add CHPL_LIBFABRIC to the list of config vars
that can override our defaults, getting rid of an incorrect and annoying
but nevertheless harmless message during compilation.