[objc] Consider new initializers inside @implementation when determining if the class
introduces new initializers.

Part of rdar://16568441

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@206409 91177308-0d34-0410-b5e6-96231b3b80d8
[objc] -[NSObject init] is documented to not do anything, don't warn if subclasses do not call [super init] on their initializers.

Part of rdar://16568441

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@206410 91177308-0d34-0410-b5e6-96231b3b80d8
Fix indentation, NFC.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@206411 91177308-0d34-0410-b5e6-96231b3b80d8