[clang] [AArch64] Remove strict checks from init-aarch64.c (PR #134338)

[Madhur Amilkanthwar via cfe-commits]

madhur13490 wrote:

> The other tests should be strengthened to always use -NEXT. The exact set of macros should be tested; don't want others hiding in the gaps

Thanks, @arsenm. However, the strict checks are creating problems in our downstream compiler and rebasing. Our downstream compiler emits some macro(s) to identify itself. Thus, we are also required to change `init-arrch64.c` test to check our downstream macro and keep CI happy. As we do rebases daily, these changes cause merge conflicts frequently.
If I segregate our downstream checks to a new file, `init-aarch64.c` will fail because checks require all macros to be back-to-back.

(Unfortunately, we cannot upstream the changes because they are very downstream-specific and inappropriate for the upstream. I am proposing this change to make our life easy.)

The checks in init-aarch64.c expect macros to be back-to-back, which seems very strict. This change aims to relax this and use just `AARCH64` instead of `AARCH64-NEXT`. This way, we maintain the order of the macros but also don't require them to be back-to-back.

Once this change is committed,  I will separate out the downstream check to a new file.
Thus, we will not have merge conflicts, and `init-aarch64.c` will continue to pass.

Does this make sense?

https://github.com/llvm/llvm-project/pull/134338