Removed the vi format comments from the source

Vim users can use the [editorconfig plugin](https://github.com/editorconfig/editorconfig-vim) to automatically set tab spacing for the SDL coding style.

Fixes https://github.com/libsdl-org/SDL/issues/6903

src/thread/pthread/SDL_systhread.c

@@ -282,5 +282,3 @@ void SDL_SYS_DetachThread(SDL_Thread *thread)
 {
     pthread_detach(thread->handle);
 }
-
-/* vi: set ts=4 sw=4 expandtab: */