Add XL compiler version check to configure

[jjhursey]

Add configure check for XL compiler version support. As indicated by various bug reports, we don't really support older XL compiler versions (<=12.1) so we should error out with an informative message.

• v3.0.0rc1: XLC-12.1 build errors w/ -q32 and atomics #3816
• v3.0.0rc1: XLC-13.1 odd failure running ring_c #3817 (somewhat related)
• v3.0.0rc1: XLC build errors with ompi_datatype_module.c #3811 (somewhat related)

It might also be useful to check for ppc64 vs ppc64le and emit a message.

[jjhursey]

Two points related to this PR:

• IBM has no objections to Open MPI discontinuing support for XL compilers older than 13.1.
• IBM has no objections to Open MPI discontinuing support for ppc64 BE Linux.

I'll add a configure time check for both of these cases and have it return a descriptive error message. Once we settle on the form of the check for master I'll PR it to the release branches.

@PHHargrove FYI: This probably impacts your testing the most.