Add taskqgroup_config_gtask_deinit to support teardown after

taskqgroup_config_gtask_init.

Approved by:	sbruno

sys/kern/subr_gtaskqueue.c

@@ -987,3 +987,9 @@ taskqgroup_config_gtask_init(void *ctx, struct grouptask *gtask, gtask_fn_t *fn,
 	GROUPTASK_INIT(gtask, 0, fn, ctx);
 	taskqgroup_attach(qgroup_config, gtask, gtask, -1, name);
 }
+
+void
+taskqgroup_config_gtask_deinit(struct grouptask *gtask)
+{
+	taskqgroup_detach(qgroup_config, gtask);
+}

sys/sys/gtaskqueue.h

@@ -63,6 +63,7 @@ void	taskqgroup_destroy(struct taskqgroup *qgroup);
 int	taskqgroup_adjust(struct taskqgroup *qgroup, int cnt, int stride);
 void	taskqgroup_config_gtask_init(void *ctx, struct grouptask *gtask, gtask_fn_t *fn,
 		const char *name);
+void	taskqgroup_config_gtask_deinit(struct grouptask *gtask);
 
 #define TASK_ENQUEUED			0x1
 #define TASK_SKIP_WAKEUP		0x2