make the vector conversion magic handle multiple results.

We now compile test2/test3 to:

_test2:
	## InlineAsm Start
	set %xmm0, %xmm1
	## InlineAsm End
	addps	%xmm1, %xmm0
	ret
_test3:
	## InlineAsm Start
	set %xmm0, %xmm1
	## InlineAsm End
	paddd	%xmm1, %xmm0
	ret

as expected.

llvm-svn: 50389