Merge branch 'rs/checkout-some-states-are-const' into maint

Code cleanup.

* rs/checkout-some-states-are-const:
  checkout: constify parameters of checkout_stage() and checkout_merged()

builtin/checkout.c

@@ -154,8 +154,8 @@ static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 	return 0;
 }
 
-static int checkout_stage(int stage, struct cache_entry *ce, int pos,
-			  struct checkout *state)
+static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
+			  const struct checkout *state)
 {
 	while (pos < active_nr &&
 	       !strcmp(active_cache[pos]->name, ce->name)) {
@@ -169,7 +169,7 @@ static int checkout_stage(int stage, struct cache_entry *ce, int pos,
 		return error(_("path '%s' does not have their version"), ce->name);
 }
 
-static int checkout_merged(int pos, struct checkout *state)
+static int checkout_merged(int pos, const struct checkout *state)
 {
 	struct cache_entry *ce = active_cache[pos];
 	const char *path = ce->name;