[clang] Honor pragmas with -ffp-contract=fast, depecate fast-honor-pragmas (PR #105746)

[Andy Kaylor via cfe-commits]

andykaylor wrote:

> Is the backend actually ready for this? Looking quickly at the backend, it looks like target-independent code is fine, but some of the target-specific code doesn't respect the "contract" flag on instructions.

Doesn't respect it in what way? Do you mean it doesn't attempt to fuse operations when "contract" is set, or it fuses when it isn't set?

https://github.com/llvm/llvm-project/pull/105746