Merge pull request #18978 from mppf/follow-18880-gasnet-O3
Don't always add -O3 to flags when compiling with gasnet
Follow-up to PR #18880.
The pkg-config .pc file we get gasnet flags from includes -O3 in the
flags, which caused a failure for the test
(which is sensitive to optimization level and skipped with --fast).
As well as failures with CHPL_UNWIND testing.
Previously the Makefile based approach avoided the -O3 by getting
only particular kinds of flags. We could do that too with the pkg-config
parsing as well but for now, just filter out the flags we don't want
after we parse them.
Reviewed by @ben-albrecht - thanks!
[x] test/runtime/stacktrace passes with CHPL_COMM=gasnet and CHPL_UNWIND=bundled
[x] full local gasnet testing