InstCombine: Only foldSelectICmpAndOr for integer types

Currently foldSelectICmpAndOr asserts if the "or" involves a vector
containing several of the same power of two. We can easily avoid this by
only performing the fold on integer types, like foldSelectICmpAnd does.

Fixes <rdar://problem/15012516>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191552 91177308-0d34-0410-b5e6-96231b3b80d8