[clang] [clang] Better bitfield access units (PR #65742)

[Nathan Sidwell via cfe-commits]

urnathan wrote:

> > 
> 
> Thinking further, several (AArch64, ARM & Loongson) targets have a 'HasUnaligned' bool in their TargetInfo objects. Perhaps the way forwards is to promote that to the base TargetInfo and just use that, rather than the bitfield-specific field I added (which just duplicates that functionality on those targets)?

I've added such a change.  The AArch64 & ARM targets record this information to determine whether a `__ARM_FEATURE_UNALIGNED` macro should be defined.  The Loongson target just needs to check the `-ual` target feature.


https://github.com/llvm/llvm-project/pull/65742