Add formatting to precommit

Signed-off-by: Matej Focko <mfocko@redhat.com>

.pre-commit-config.yaml

@@ -14,3 +14,10 @@ repos:
       - id: check-rebase
         args:
           - https://git.mfocko.xyz/mfocko/precommit-example.git
+-   repo: local
+    hooks:
+      - id: formatting
+        name: format source
+        entry: make format
+        language: system
+        pass_filenames: false

main.c

@@ -1,6 +1,4 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-int main() {
+int main() { return NULL; }
-    return NULL;
-}