Re-add reporting of load time versions of NSS and NSPR libraries

Meanwhile that functionality exists for several years,
and a recent firefox version requires much newer library versions
than about 2 years ago.
Mute bogus OpenMP warnings when running MPI.
Revert to using rexgen if found, but only if it's the version we
support. We can expand this to recognize newer versions once
we support them. You can still use --disable-rexgen to manually
disable it.
Merge pull request #695 from frank-dittrich/bleeding-jumbo

Re-add reporting of load time versions of NSS and NSPR libraries
Workaround for buggy CUDA memcpy() of length 0 in md5crypt.
Drop the SHA2 ng-i formats. They were interim ones before the
generic ones got SIMD support. Closes #677
RIPE-MD128/160 bug fixes. Closes #675
Oracle, unify case in split(). Closes #657.
For FMT_NOT_EXACT, --show=left should only output hashes we did
not found *any* candidate for. Closes #671.
"Found no" or "did not find any", pick one.