[InitUndef] Also handle inline asm (#108951)
InitUndef should also handle early-clobber / undef conflicts in inline
asm operands. Do this by iterating over all_defs() instead of defs().
The newly added ARM test was generating an "unpredictable STXP instruction,
status is also a source" error prior to this change.
Fixes https://github.com/llvm/llvm-project/issues/106380.
