OpenBLAS @0.3.4_1 forces system AR and RANLIB but this errors on older systems

[kencu (Ken)]

The Portfile does this:

# Using system ones as default is set to bin/gcc-ar which does not
# exist, and using gcc-mp ones end up in an error about a missing
# plugin. (see ticket #38551 for example)
build.args          "AR=/usr/bin/ar RANLIB=/usr/bin/ranlib"

but on some systems, that results in the following, because the system cctools are too old to understand the objects coming out of the newer compilers (usually clang-3.9+):

ar: creating archive ../libopenblas-r1.a
/usr/bin/ranlib: object: ../libopenblas-r1.a(comatcopy.o) malformed object (unknown load command 2)
/usr/bin/ar: internal ranlib command failed
make[1]: *** [libs] Error 1
make[1]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_math_OpenBLAS/OpenBLAS/work/OpenBLAS-0.3.4/interface'

I don't presently have a well-thought-out plan for what to do with this issue. This force went into the Portfile a long time ago for a gcc related issue. Deleting the line forcing AR and RANLIB works well enough. Which systems crossed with which compilers has not been fully worked out yet.