[X86] When type legalizing the result of a i64 fp_to_uint on 32-bit targets....

[X86] When type legalizing the result of a i64 fp_to_uint on 32-bit targets. Generate all of the ops as i64 and let them be legalized.

No need to manually split everything. We can let the type legalizer work for us.

The test change seems to be caused by some DAG ordering issue that was previously circumventing a one use check in LowerSELECT where FP selects are turned into blends if the setcc has one use. But it was running after an integer select and the same setcc had been legalized to cmov and X86SISD::CMP. This dropped the use count of the setcc, but wasn't what was intended.

llvm-svn: 354197