Bug: gather/scatter accepts same registers in destination/src and index

[Michael Zolotukhin]

Hi HJ, Jan,

I looked at the bug, spotted by Jan:

        # destination and index the same being accepted
        vgatherqps      ymm0{k1}, [eax+zmm0]
        vpgatherqd      ymm0{k1}, [eax+zmm0]

The patch is ready, and the remaining question is how to add
corresponding tests. Should they be added to 'vgather-check.s',
'x86-64-vgather-check.s' or should they be placed separately? Also,
this problem touches scatters as well, so in case we want to have a
single file for these tests, it probably should be renamed. What do
you think?

Thanks,
Michael