Consider the base pointer for setting the symbol type.

This is really a consistency fix. Since given

a = b

we propagate the information, we should propagate it too given

a = b + (1 - 1)

Fixes pr19145.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204028 91177308-0d34-0410-b5e6-96231b3b80d8