Revert r212572 "improve BasicAA CS-CS queries", it causes PR20303.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213024 91177308-0d34-0410-b5e6-96231b3b80d8
Teach GetUnderlyingObject / BasicAA about addrspacecast

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213025 91177308-0d34-0410-b5e6-96231b3b80d8