x86emul: add support for missing {,V}PMADDWD insns

x86emul: add support for missing {,V}PMADDWD insns

Their pre-AVX512 incarnations have clearly been overlooked during much
earlier work. Their memory access pattern is entirely standard, so no
specific tests get added to the harness.

Reported-by: Razvan Cojocaru <rcojocaru@bitdefender.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Tested-by: Alexandru Isaila <aisaila@bitdefender.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 1a48bdd599b268a2d9b7d0c45f1fd40c4892186e
master date: 2019-05-16 13:43:17 +0200