[clang] Always honor fp-contract pragmas on PlayStation (PR #162549)

[via cfe-commits]

wjristow wrote:

The test-case of this patch generates X86 assembly code, rather than the usual approach of generating generic IR.  The reason I did that is because the impact of the change isn't visible in the IR.  That's due to a bug, which I've just filed: https://github.com/llvm/llvm-project/issues/162550

If this patch is accepted, we will want to update the documentation of `-ffp-contract=<value>`:
https://clang.llvm.org/docs/UsersManual.html#cmdoption-ffp-contract

For reference, here are some points of discussion about the `-ffp-contract=fast-honor-pragmas` concept:
https://discourse.llvm.org/t/fp-contract-fast-and-pragmas/58529
https://discourse.llvm.org/t/rfc-honor-pragmas-with-ffp-contract-fast/80797/14

https://github.com/llvm/llvm-project/pull/162549