[llvm] [ARM] Allow spilling FPSCR for MVE adc/sbc intrinsics (PR #115174)

[Simon Tatham via llvm-commits]

https://github.com/statham-arm approved this pull request.

LGTM. (Also, today I learned that there are VLDR/VSTR instructions specifically for the flags part of FPSCR, as well as for FPSCR as a whole.)

https://github.com/llvm/llvm-project/pull/115174