gdb/record: Add support for more vmov-style instructions

This commit adds support for a few more vmov instructions:
* VMOV[LH|HL]PS
* VMOVLPD
* VMOVHP[S|D]
* VMOVDDUP

And associated tests. The testsuite had some minor re-working, adding a
function to zero buffers, to make later tests less fragile.