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

[Martin Storsjö via cfe-commits]

mstorsjo wrote:

This is a smaller, self-isolated change split out from #130623 - in order to fix a regression from 8fa0f0efce5fb81eb422e6d7eec74c66dafef4a3 as noted by @anemet in https://github.com/llvm/llvm-project/pull/122095#discussion_r2027399582; in a form that hopefully can be considered for backporting to 20.x.

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