Merge commit c97a7675eea4 from llvm git (by Qiu Chaofan):

[PowerPC] Expand FSINCOS of fp128 (#76494)

This fixes "fatal error: error in backend: Cannot select: 0x6d420285c0:
f128,f128 = fsincos 0x6d4202b6f0" when compiling s_cpowl.c for
powerpc64le.

Upstream ticket: https://github.com/llvm/llvm-project/issues/76442

Reported by: pkubaj
MFC after: 3 days

(cherry picked from commit 79639686401bedbcbbf04eb71e0acb1cc7dcbbcb)