[JumpThreading] When processing compares, explicitly check that the result...

[JumpThreading] When processing compares, explicitly check that the result type is not a vector rather than check for it being an integer.

Compares always return a scalar integer or vector of integers. isIntegerTy returns false for vectors, but that's not completely obvious. So using isVectorTy is less confusing.

llvm-svn: 302198