X86ISelLowering: Only perform copy elision on legal types.

This fixes cases where i1 types were not properly legalized yet and lead
to the creating of 0-sized stack slots.

This fixes http://llvm.org/PR32136

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296950 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed