[llvm] [X86] Treat returns as SpecialFP values (PR #83615)

[Craig Topper via llvm-commits]

topperc wrote:

The coverage report says that handleReturn is called https://lab.llvm.org/coverage/coverage-reports/coverage/Users/buildslave/jenkins/workspace/coverage/llvm-project/llvm/lib/Target/X86/X86FloatingPoint.cpp.html#L1073

https://github.com/llvm/llvm-project/pull/83615