RFR(M): 8213528: fp registers should not need to be saved around a CallLeafNoFP

[Roland Westrelin]

> I think NO_FP code was added mostly for x86 FPU and SPARC float registers.
> Now on x86 we use XMM registers almost in all intrinsics so the original assumption is not true anymore on *x86*.
> It is still true on other platforms (SPARC?). May be we should factor out it somehow to be platform specific?

It sounds like something that could be build on top of this change
rather than something that needs to be part of this change? Or do you
have a specific idea in mind?

Roland.