GEBS_CMD() convinience macro

example/gebs.c

@@ -5,14 +5,9 @@ int main(int argc, char ** argv)
 {
     gebs_rebuild_self(argc, argv, "cc", "-o", "gebs", __FILE__);
 
-    Gebs_Cmd cmd = {0};
-    gebs_cmd_append(&cmd, "cc");
-    gebs_cmd_append(&cmd, "main.c");
-
-    int ec = gebs_cmd_run(&cmd);
-    printf("%d\n", ec);
-
-    gebs_cmd_free(&cmd);
-
+    if (GEBS_CMD("gcc", "-o", "main", "main.c") != 0) {
+        return 1;
+    }
+    
     return 0;
 }