x86emul: complete support of AVX512_VBMI insns

x86emul: complete support of AVX512_VBMI insns

Also add testing of ones support for which was added before. Sadly gcc's
command line option naming is not in line with Intel's naming of the
feature, which makes it necessary to mis-name things in the test harness.

Since the only new insn here and in particular its memory access pattern
follows the usual scheme, I didn't think it was necessary to add a
contrived test specifically for it, beyond the Disp8 scaling one.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>