clang-format: Format Objective-C try blocks like all the other try blocks.

Before:

  @try {
    // ...
  }
  @finally {
    // ...
  }

Now:

  @try {
    // ...
  } @finally {
    // ...
  }

This is consistent with how we format C++ try blocks and SEH try blocks.
clang-format not doing this before was an implementation oversight.

This is dependent on BraceBreakingStyle.  The snippet above is with the
Attach style.  Style Stroustrip for example still results in the "Before:"
snippet, which makes sense since other blocks (try, else) break after '}' too.

llvm-svn: 228483