[clang-format] Don't allow newline after uppercase Obj-C block return types

Fixes the following:
  BOOL (^aaa)(void) = ^BOOL {
  };

The first BOOL's token was getting set to TT_FunctionAnnotationRParen
incorrectly, which was causing an unexpected newline after (^aaa). This
was introduced in r245846.

Patch by Kent Sutherland, thank you!

llvm-svn: 282448