entry.c: Use const qualifier for 'struct checkout' parameters

index 89aaf00..fe1e2e8 100644
@@ -377,7 +377,7 @@ struct checkout {
 		 refresh_cache:1;
 };
 
-extern int checkout_entry(struct cache_entry *ce, struct checkout *state, char *topath);
+extern int checkout_entry(struct cache_entry *ce, const struct checkout *state, char *topath);
 
 extern struct alternate_object_database {
 	struct alternate_object_database *next;

index b51addb..82bf725 100644
@@ -1,7 +1,7 @@
 #include "cache.h"
 #include "blob.h"
 
-static void create_directories(const char *path, struct checkout *state)
+static void create_directories(const char *path, const struct checkout *state)
 {
 	int len = strlen(path);
 	char *buf = xmalloc(len + 1);

@@ -75,7 +75,7 @@ static void *read_blob_entry(struct cache_entry *ce, const char *path, unsigned
 	return NULL;
 }
 
-static int write_entry(struct cache_entry *ce, char *path, struct checkout *state, int to_tempfile)
+static int write_entry(struct cache_entry *ce, char *path, const struct checkout *state, int to_tempfile)
 {
 	int fd;
 	long wrote;

@@ -163,7 +163,7 @@ static int write_entry(struct cache_entry *ce, char *path, struct checkout *stat
 	return 0;
 }
 
-int checkout_entry(struct cache_entry *ce, struct checkout *state, char *topath)
+int checkout_entry(struct cache_entry *ce, const struct checkout *state, char *topath)
 {
 	static char path[PATH_MAX + 1];
 	struct stat st;