[InstCombine] allow bitcast to/from FP for vector insert/extract transform

This is a follow-up to rL343482 / D52439.
This was a pattern that initially caused the commit to be reverted because
the transform requires a bitcast as shown here.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@343794 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed