Revert "loop: deprecate the hooks"

This reverts commit 550ec8c2a4.

Before hooks are still useful when integrating other fds in the pipewire
main loop.

spa/include/spa/support/loop.h

@@ -191,17 +191,15 @@ SPA_API_LOOP int spa_loop_locked(struct spa_loop *object,
 
 /** Control hooks. These hooks can't be removed from their
  *  callbacks and must be removed from a safe place (when the loop
- *  is not running or when it is locked).
- *
- *  \deprecated This was used to lock and unlock the loop but because
- *  this is now standard behaviour, these extra hooks are not very
- *  useful anymore. */
+ *  is not running or when it is locked). */
 struct spa_loop_control_hooks {
 #define SPA_VERSION_LOOP_CONTROL_HOOKS	0
 	uint32_t version;
-	/** Executed right before waiting for events. \deprecated */
+	/** Executed right before waiting for events. It is typically used to
+	 * release locks or integrate other fds into the loop. */
 	void (*before) (void *data);
-	/** Executed right after waiting for events. \deprecated */
+	/** Executed right after waiting for events. It is typically used to
+	 * reacquire locks or integrate other fds into the loop. */
 	void (*after) (void *data);
 };