Enable -Wunused-private-field with -Wunused.

It found a lot of cruft in LLVM that I removed last week and I couldn't find any
false positives. Time to give it more testing.

llvm-svn: 158317

clang/include/clang/Basic/DiagnosticGroups.td

@@ -312,7 +312,7 @@ def Unused : DiagGroup<"unused",
                        [UnusedArgument, UnusedFunction, UnusedLabel,
                         // UnusedParameter, (matches GCC's behavior)
                         // UnusedMemberFunction, (clean-up llvm before enabling)
-                        // UnusedPrivateField, (clean-up llvm before enabling)
+                        UnusedPrivateField,
                         UnusedValue, UnusedVariable]>,
                         DiagCategory<"Unused Entity Issue">;
 

clang/test/FixIt/fixit.cpp

@@ -54,7 +54,7 @@ namespace rdar7853795 {
 }
 
 namespace rdar7796492 {
-  class A { int x, y; A(); };
+  struct A { int x, y; A(); };
 
   A::A()
     : x(1) y(2) { // expected-error{{missing ',' between base or member initializers}}