Revert r148901 because it crashes llvm tests.

Original log:
    Introduce a new ConstantVector::getSplat constructor function to
    simplify a really common case.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148906 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed