fenv.h support

[Stathis Kamperis <ekamperi%gmail.com@localhost>]

Hi people.

I have a very preliminary attempt to add support for fenv.h interface for sparc.
Source is here: http://leaf.dragonflybsd.org/~beket/sparc-fenv.diff

It is a remnant from the Google Summer of code era. I don't have
enough time to continue working on it, and most importantly I don't
have access to sparc h/w. I only once cross-built NetBSD in a i386
host (after applying the patch). So maybe it doesn't even apply
cleanly or build fine now.

If anyone feels like hacking on it, that would rock as the effort
wouldn't go down the toilet :)
I could also provide some help in form of w/e expertise I gathered
during summer and guidance on how to properly test the implementation
(we have already a bunch of fenv-related test cases).

Look forward to hearing you from you people and answering any questions.

Best regards,
Stathis