fenv soft-float support

Hello,

the recent fenv patches added support for the soft-float implementation 
of FreeBSD. Newlib uses the one from libgcc by default. They are not 
compatible. Having an GCC incompatible soft-float fenv support in Newlib 
makes no sense to me.

How can we fix this?

As a short-term fix, I would remove the FreeBSD fenv support. What 
should we provide instead? I would just provide the hardware 
implementation of the architecture for now. If someone uses this in a 
soft-float configuration, he may get exceptions or some sort of 
undefined behaviour. This is what you get on powerpc currently.

A long-term solution would be to add support for the GCC soft-float 
implementation in libgcc. This requires changes in the GCC 
configuration. I guess this is a bit of work.