libcamera: base: Make message.h and mutex.h private

The message.h and mutex.h headers are not used in the libcamera public
API. Make them private to avoid there usage in applications, and to
prevent having to maintain them with a stable ABI.

As mutex.h is used by libcamerasrc, the GStreamer element must switch
from the libcamera_public to the libcamera_private dependency.

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

include/libcamera/base/message.h

@@ -9,6 +9,8 @@
 
 #include <atomic>
 
+#include <libcamera/base/private.h>
+
 #include <libcamera/base/bound_method.h>
 
 namespace libcamera {

include/libcamera/base/mutex.h

@@ -10,6 +10,8 @@
 #include <condition_variable>
 #include <mutex>
 
+#include <libcamera/base/private.h>
+
 #include <libcamera/base/thread_annotations.h>
 
 namespace libcamera {