[clang] [clang] Allow `ConditionalOperator` fast-math flags to be overridden by `pragma float_control` (PR #105912)

[John McCall via cfe-commits]

rjmccall wrote:

Oh, that's interesting. I'd been assuming this was a cross-function issue or something like that, but that's a great example of where we need more than that.  I agree that it feels like having some kind of barrier instruction is the right way to go — basically a unary operator that can have fast-math restrictions on its operand/result just like all the binary operators and intrinsics do, and then we can decide the right places to emit that.

https://github.com/llvm/llvm-project/pull/105912