FS-4850: Make cache db get_handle call not return handles which are already in use.

src/switch_core_sqldb.c

@@ -144,7 +144,7 @@ static switch_cache_db_handle_t *get_handle(const char *db_str, const char *user
 	switch_mutex_lock(sql_manager.dbh_mutex);
 
 	for (dbh_ptr = sql_manager.handle_pool; dbh_ptr; dbh_ptr = dbh_ptr->next) {
-		if (dbh_ptr->thread_hash == thread_hash && dbh_ptr->hash == hash &&
+		if (dbh_ptr->thread_hash == thread_hash && dbh_ptr->hash == hash && !dbh_ptr->use_count &&
 			!switch_test_flag(dbh_ptr, CDF_PRUNE) && switch_mutex_trylock(dbh_ptr->mutex) == SWITCH_STATUS_SUCCESS) {
 			r = dbh_ptr;
 		}