[x86 testing] NFC: Create exhaustive vector popcnt ULT/UGT tests

There are bunch of optimization opportunities right now in the vector
popcnt code gen when doing simple less-than/greater-than comparisons, so
let's examine them all to ensure that things don't regress as different
scenarios are fixed. We can always delete some later once some fixes are
made.

Please note: the new files were auto-generated. If people want, I can
commit the short C code that printed out the various combinations.