[analyzer] Change the way in which IDC Visitor decides to kick in and make sure it attaches in the given edge case

In the test case below, the value V is not constrained to 0 in ErrorNode but it is in node N.
So we used to fail to register the Suppression visitor.

We also need to change the way we determine that the Visitor should kick in because the node N belongs to
the ExplodedGraph and might not be on the BugReporter path that the visitor sees. Instead of trying to match the node,
turn on the visitor when we see the last node in which the symbol is ‘0’.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@177121 91177308-0d34-0410-b5e6-96231b3b80d8
Add a testcase for r177118.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@177124 91177308-0d34-0410-b5e6-96231b3b80d8
Don't try to typo-correct 'super' in an objc method.

This created 2 issues:

1) Performance issue, since typo-correction with PCH/modules is rather expensive.
2) Correctness issue, since if it managed to "correct" 'super' then bogus compiler errors would
be emitted, like this:

3.m:8:3: error: unknown type name 'super'; did you mean 'super1'?
  super.x = 0;
  ^~~~~
  super1
t3.m:5:13: note: 'super1' declared here
typedef int super1;
            ^
t3.m:8:8: error: expected identifier or '('
  super.x = 0;
       ^

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@177126 91177308-0d34-0410-b5e6-96231b3b80d8