[llvm] [X86] Support EVEX compression from MOVBErr to BSWAP (PR #79775)

[Simon Pilgrim via llvm-commits]

RKSimon wrote:

@XinWang10 I'm seeing an expensive checks error that I think is due to this commit:
```
# After Compressing EVEX instrs when possible
# Machine code for function bswapr_to_movberr: IsSSA, NoPHIs, NoVRegs

bb.0.entry:
  renamable $rax = BSWAP64r killed renamable $rax
  RET64 killed $rax

# End machine code for function bswapr_to_movberr.

*** Bad machine code: Operand should be tied ***
- function:    bswapr_to_movberr
- basic block: %bb.0 entry (0x1ba33239778)
- instruction: renamable $rax = BSWAP64r killed renamable $rax
- operand 1:   killed renamable $rax
LLVM ERROR: Found 1 machine code errors.
```

https://github.com/llvm/llvm-project/pull/79775