clang-format: Format array and dict literals similar to blocks.

Especially, reduce the amount of indentation if it doesn't increase
readability.

Before:
  NSMutableDictionary* dictionary = [NSMutableDictionary
      dictionaryWithDictionary:@{
                                 aaaaaaaaaaaaaaaaaaaaa : aaaaaaaaaaaaa,
                                 bbbbbbbbbbbbbbbbbb : bbbbb,
                                 cccccccccccccccc : ccccccccccccccc
                               }];

After:
  NSMutableDictionary* dictionary =
      [NSMutableDictionary dictionaryWithDictionary:@{
        aaaaaaaaaaaaaaaaaaaaa : aaaaaaaaaaaaa,
        bbbbbbbbbbbbbbbbbb : bbbbb,
        cccccccccccccccc : ccccccccccccccc
      }];

llvm-svn: 209720