SSE2 builtins support part 2

[Jan Hubicka]

> This adds the necessary support in xmmintrin.h.   While doing it, I noticed
> a number of bugs and oddities which are also fixed by this patch.

Great. So the SSE2 support should be complette now?

There is need to update the attributes of the new instruction patterns
for new scheduling implementation. I can do it later.
Also the bugs probably should be fixed on the branch once it re-opens.

Whats about the stack alignment issues?

Honza