[analyzer] Look for a StmtPoint node instead of PostStmt in trackNullOrUndefValue.

trackNullOrUndefValue tries to find the first node that matches the statement it is tracking.
Since we collect PostStmt nodes (in node reclamation), none of those might be on the
current path, so relax the search to look for any StmtPoint.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178380 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed