Add VSELECT to LegalizeVectorTypes::ScalariseVectorResult. Previously it...

Add VSELECT to LegalizeVectorTypes::ScalariseVectorResult.  Previously it would crash if it encountered a 1 element VSELECT.  Solution is slightly more complicated than just creating a SELET as we have to mask or sign extend the vector condition if it had different boolean contents from the scalar condition.  Fixes <rdar://problem/11178095>

llvm-svn: 153976