Add cache.h

The functions found in cache.c are only used by cgit.c, so there's no
point in rebuilding all object files when the cache interface is changed.


Signed-off-by: Lars Hjemli <hjemli@gmail.com>

cache.h

@@ -0,0 +1,23 @@
+/*
+ * Since git has it's own cache.h which we include,
+ * lets test on CGIT_CACHE_H to avoid confusion
+ */
+
+#ifndef CGIT_CACHE_H
+#define CGIT_CACHE_H
+
+struct cacheitem {
+	char *name;
+	struct stat st;
+	int ttl;
+	int fd;
+};
+
+extern char *cache_safe_filename(const char *unsafe);
+extern int cache_lock(struct cacheitem *item);
+extern int cache_unlock(struct cacheitem *item);
+extern int cache_cancel_lock(struct cacheitem *item);
+extern int cache_exist(struct cacheitem *item);
+extern int cache_expired(struct cacheitem *item);
+
+#endif /* CGIT_CACHE_H */