libcamera: base: Move thread_annotations to private

The libcamera thread annotations are for internal use only and are
not part of any public API. Mark the header accordingly by including the
private.h header guard.

Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

include/libcamera/base/thread_annotations.h

@@ -7,6 +7,8 @@
 
 #pragma once
 
+#include <libcamera/base/private.h>
+
 /*
  * Enable thread safety attributes only with clang.
  * The attributes can be safely erased when compiling with other compilers.