Try to correct a mistyped "-" or ">" to "->" for some C++ cases.

Similar C code isn't caught as it seems to hit a different code path.
Also, as the check is only done for record pointers, cases involving
an overloaded operator-> are not handled either. Note that the reason
this check is done in the parser instead of Sema is not related to
having enough knowledge about the current state as it is about being
able to fix up the parser's state to be able to recover and traverse the
correct code paths.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194002 91177308-0d34-0410-b5e6-96231b3b80d8