[llvm] [AArch64] Fix handling of x29/x30 in inline assembly clobbers (PR #167783)

[Lukáš Lalinský via llvm-commits]

lalinsky wrote:

Ok, I'll restrict this to just x29/x30 and update everything accordingly 

The one test is sketchy though. I don't fully understand it, but I think the CHECKS actually check that the compiler can store data in x29, despite it being added to the clobber list. A proper fix would be update the checks to make sure it uses x30, which is not clobbered. I'd like to do that, but I'd have to dig a lot deeper to understand the exact output.

https://github.com/llvm/llvm-project/pull/167783