As of D80952 we are disabling strict floating point on all hosts except those that are explicitly listed as supported. Use of strict floating point on other hosts requires use of the -fexperimental-strict-floating-point flag. This is to avoid bugs like "https://bugs.llvm.org/show_bug.cgi?id=45329" (which has an incorrect link in the previous review).
In the review for D80952 I was asked to mark the -fexperimental option as a MarshallingInfoFlag. This patch does exactly that.
The previous tests continue to work correctly so I haven't included a new one here. I can if needed, but I would need guidance since I don't know what would need to be tested.