AVX Naming

When Bruno designed the AVX spec, it looks like he created names like:

VADDPSrm
VADDPSYrm

to distinguish 128-bit and 256-bit operation. It's sort of become a
personal hobby of mine to curse the binutils maintainers for
"vcvtpd2psy" because it's so easy to miss the trailing suffix on a quick
scan.

I find that same trouble reading dumps with the current AVX names.
Before regalloc it is harder to determine the vector length of an
instruction at a glance.

To overcome that, I started using a naming convention of:

VxADDSSrm
VxADDPSrm
VyADDPSrm

What do people think? I realize it's "only" naming but when scannig
debug dumps I've found it really helpful to quicky determine how
something was vectorized. From a performance debugging standpoint,
vector length is often an indication of problems or missed
opportunities.

I'm willing to do a gradual mechanical change if this seems reasonable
to people.

                             -Dave