[llvm] [AArch64] Refactor @plt, @gotpcrel, and @AUTH to use parseDataExpr (PR #134202)

[David Benjamin via llvm-commits]

davidben wrote:

Ah yeah, our asm files also don't yet set `.subsections_via_symbols` (or emit `-ffunction-sections`-like code) because the asm is derived from OpenSSL, which likes to play tricks like this. We have a bug open to change this, but would require a bit of work to make sure it won't break: https://issues.chromium.org/issues/42290614

https://github.com/llvm/llvm-project/pull/134202