clang-format: Fix ObjC block as first call parameter formatting.

Before:
  foo (^{ bar(); });
After:
  foo(^{ bar(); });

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@199573 91177308-0d34-0410-b5e6-96231b3b80d8
[CMake] check-clang requires clang-tblgen. It is not required by anyone when external CLANG_TABLEGEN is specified.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@199579 91177308-0d34-0410-b5e6-96231b3b80d8
clang-format: Better support and testing for protocol buffers.

With this patch, there is dedicated testing for protocol buffers
(https://developers.google.com/protocol-buffers/).

Also some minor tweaks formatting tweaks.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@199580 91177308-0d34-0410-b5e6-96231b3b80d8