libcamera: Document thread-safety attributes of core classes

Define the thread-safety attributes of the classes and methods that are
either thread-safe or thread-bound. The CameraManager, Camera and
PipelineHandler will be addressed separately.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

src/libcamera/ipc_unixsocket.cpp

@@ -62,6 +62,8 @@ LOG_DEFINE_CATEGORY(IPCUnixSocket)
  * communication method. The remote side then instantiates a socket, and binds
  * it to the other side by passing the file descriptor to bind(). At that point
  * the channel is operation and communication is bidirectional and symmmetrical.
+ *
+ * \context This class is \threadbound.
  */
 
 IPCUnixSocket::IPCUnixSocket()