x87: Avoid pushing (ia32 specific) noreg onto stack
x87: Avoid pushing (ia32 specific) noreg onto stack

The former behaviour was an ad-hoc measure to avoid searching for a free
virtual x87 register. The existence of the NOREG is an ia32 detail
though and does not work with amd64.

jonashaag/libfirm,jonashaag/libfirm,libfirm/libfirm,MatzeB/libfirm,libfirm/libfirm,libfirm/libfirm,libfirm/libfirm,MatzeB/libfirm,MatzeB/libfirm,jonashaag/libfirm,MatzeB/libfirm,libfirm/libfirm,jonashaag/libfirm,jonashaag/libfirm,jonashaag/libfirm,MatzeB/libfirm,MatzeB/libfirm,jonashaag/libfirm,MatzeB/libfirm