[FPEnv][X86] Correct one more strictfp test.

Correct a strictfp test to follow the rules documented in the
LangRef:
https://llvm.org/docs/LangRef.html#constrained-floating-point-intrinsics

This test needed the strictfp attribute added to some function
definitions. FP wait instructions now appear as a result. The need
for the wait instructions is explained by Andy Kaylor in PR#87791:
https://github.com/llvm/llvm-project/pull/87791

Test changes verified with D146845.