general: recoded snd_dlobj_ functions

- changed logic to get/put blocks
- added mutex locking of the symbol list
- added reference counting (do not free used dl handles)

Signed-off-by: Jaroslav Kysela <perex@perex.cz>

src/control/control_local.h

@@ -56,7 +56,7 @@ typedef struct _snd_ctl_ops {
 
 
 struct _snd_ctl {
-	void *dl_handle;
+	void *open_func;
 	char *name;
 	snd_ctl_type_t type;
 	const snd_ctl_ops_t *ops;