[db] Make the db connection static
diff --git a/src/db.c b/src/db.c
index 9c4c378..87b41bd 100644
--- a/src/db.c
+++ b/src/db.c
@@ -31,7 +31,7 @@
 
 static char *db_basename = NULL;
 static char *db_dirname = NULL;
-dbi_conn conn;
+static dbi_conn conn;
 static struct gsm_network *current_network = NULL;
 
 static char *create_stmts[] = {