[clang] [Clang] [ARM] Ensure FPU Features are collected when using the Clang Assembler (PR #134366)

[David Green via cfe-commits]

davemgreen wrote:

I was going to suggest in #130623 that we undid this part of the change and made it an NFC except for  +[no]simd. But after looking at it this morning.. I wasn't sure. It at least it deserved to be its own change :)

I believe that if it used `if (!ForAS || !Generic)` then it would be the same as it was in the past, but get the features correct for the driver->cc1as.

I would expect that for the same options, assembly and C compiles would have the same features enabled. That sounds like a sensible way for a compiler to behave. But I would expect the preprocessor and assembler to have the same features when compiling the same file but that doesn't appear to always happen at the moment.

https://github.com/llvm/llvm-project/pull/134366