Formatter: Add space before '(' in @implemenation, @interface, @protocol lines

The first token in @implementation, @interface, and @protocol lines is now
marked TT_ObjCDecl, and lines starting with a TT_ObjCDecl token are now marked
LT_ObjCMethodDecl.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@172093 91177308-0d34-0410-b5e6-96231b3b80d8