Fix FP_TO_UINT with Scalar SSE2 now that the legalizer can handle it. We

Fix FP_TO_UINT with Scalar SSE2 now that the legalizer can handle it.  We
now generate the relatively good code sequences:
unsigned short foo(float a) { return a; }
_foo:
        movss 4(%esp), %xmm0
        cvttss2si %xmm0, %eax
        movzwl %ax, %eax
        ret

and
unsigned bar(float a) { return a; }
_bar:
        movss .CPI_bar_0, %xmm0
        movss 4(%esp), %xmm1
        movapd %xmm1, %xmm2
        subss %xmm0, %xmm2
        cvttss2si %xmm2, %eax
        xorl $-2147483648, %eax
        cvttss2si %xmm1, %ecx
        ucomiss %xmm0, %xmm1
        cmovb %ecx, %eax
        ret

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22786 91177308-0d34-0410-b5e6-96231b3b80d8