Patch to check unimplemented method declared in objc class extensions

This patch uses the new ObjCImplDecl class to merge Sema::ImplMethodsVsClassMethods and Sema::ImplCategoryMethodsVsIntfMethods methods.
And now, when clang check a class implementation to find unimplemented methods, it also checks all methods from the class extensions (unnamed categories).

There is also a test case to check this warning.

This patch contains also a minor update for ObjCImplDecl . getNameAsCString and getNameAsString now returns an empty string instead of crashing for unnamed categories.

warn-objc-ext.patch (10.8 KB)

nice! Applied: