reapply r148902:

"use the new ConstantVector::getSplat method where it makes sense."

Also simplify a bunch of code to use the Builder->getInt32 instead
of doing it the hard and ugly way.  Much more progress could be made
here, but I don't plan to do it.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@148926 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed