parse identifier expressions properly. This allows us diagnose this:

typedef int X;

int A() {
  return X;
}

int B() {
  return Y;
}

as:

/Users/sabre/test.c:5:10: error: unexpected type name 'X': expected expression
return X;
       ^
/Users/sabre/test.c:9:10: error: use of undeclared 'Y' value
return Y;
       ^

llvm-svn: 39192