improve diagnostics on missing ; in a struct. Before:

t.c:4:3: error: expected ';' at end of declaration list
  int y;
  ^
t.c:4:8: warning: extra ';' inside a struct or union
  int y;
       ^
t.c:6:1: warning: expected ';' at end of declaration list
};
^

After:

t.c:3:8: error: expected ';' at end of declaration list
  int x  // expected-error {{expected ';' at end of declaration list}}
       ^
       ;
t.c:5:8: warning: expected ';' at end of declaration list
  int z
       ^
       ;

llvm-svn: 95038