AST: Small code cleanup

Move the pointer to be adjacent to the variable instead of the type.

No functional change.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@202089 91177308-0d34-0410-b5e6-96231b3b80d8
Improve some gtest assertions

As requested during review, compare pointers to NULL explicitly to make what's
going on more clear.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@202090 91177308-0d34-0410-b5e6-96231b3b80d8