change switch_strlen_zero to zstr

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@15211 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/switch_swig.c

@@ -49,7 +49,7 @@ int fs_core_init(char *path)
 	switch_status_t status;
 	const char *err = NULL;
 
-	if (switch_strlen_zero(path)) {
+	if (zstr(path)) {
 		path = NULL;
 	}