Fix a constant folding address space place I missed.

If address space 0 was smaller than the address space
in a constant inttoptr/ptrtoint pair, the wrong mask size
would be used.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190899 91177308-0d34-0410-b5e6-96231b3b80d8