gbm: Fix a debug log message

Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>

src/gbm/backends/dri/gbm_dri.c

@@ -336,7 +336,7 @@ dri_open_driver(struct gbm_dri_device *dri)
    }
 
    if (dri->driver == NULL) {
-      fprintf(stderr, "gbm: failed to open any driver (search paths %s)",
+      fprintf(stderr, "gbm: failed to open any driver (search paths %s)\n",
               search_paths);
       return NULL;
    }