Revert r151638 because it causes assertion hit on PCH creation for Cocoa.h

Original log:
---------------------
Correctly track tags and enum members defined in the prototype of a function, and ensure they are properly scoped.

This fixes code such as:

enum e {x, y};
int f(enum {y, x} n) {
 return 0;
}

This finally fixes PR5464 and PR5477.
---------------------

I also reverted r151641 which was enhancement on top of r151638.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@151667 91177308-0d34-0410-b5e6-96231b3b80d8
15 files changed