"Fix" some unintentional fallout from converting

the Stmt* visitation in CursorVisitor to be
data-recursive.

Since AnnotationTokensWorker explicitly calls
CursorVisitor::VisitChildren(), it essentially
transforms the data-recursive algorithm in
CursorVisitor back into a non-data recursive one.
This is particularly bad because the data-recursive
algorithm uses more stack space per stack frame,
which can cause us to blow the stack in some cases.

"Fix" this by making the stack that AnnotationTokensWorker
runs in really huge.  The real fix is to modify
AnnotationTokensWorker not to do the explicit
recursive call.

llvm-svn: 119047