Introduce a parsing action to distinguish between class, instance, and

Introduce a parsing action to distinguish between class, instance, and
super message sends in Objective-C. No actual functionality change
here, but it provides a hook so that Sema can typo-correct the
receiver in some cases.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@101207 91177308-0d34-0410-b5e6-96231b3b80d8