x86emul: test coverage for SSE/SSE2 insns

x86emul: test coverage for SSE/SSE2 insns

... and their AVX equivalents. Note that a few instructions aren't
covered (yet), but those all fall into common pattern groups, so I
would hope that for now we can do with what is there.

MMX insns aren't being covered at all, as they're not easy to deal
with: The compiler refuses to emit such for other than uses of built-in
functions.

The current way of testing AVX insns is meant to be temporary only:
Once we fully support that feature, the present tests should rather be
replaced than full ones simply added.

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