Formatter: @optional and @required go on their own line.

Previously:
@protocol myProtocol
- (void)mandatoryWithInt:(int)i;
@optional - (void) optional;
@required - (void) required;
@end

Now:
@protocol myProtocol
- (void)mandatoryWithInt:(int)i;
@optional
- (void)optional;
@required
- (void)required;
@end

llvm-svn: 172023