merge(third_party/cgit): Import at master of 2020-01-11

Imported commit '723dc8fbcb' as
'third_party/cgit'.

third_party/cgit/cache.h

@@ -0,0 +1,37 @@
+/*
+ * 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
+
+typedef void (*cache_fill_fn)(void);
+
+
+/* Print cached content to stdout, generate the content if necessary.
+ *
+ * Parameters
+ *   size    max number of cache files
+ *   path    directory used to store cache files
+ *   key     the key used to lookup cache files
+ *   ttl     max cache time in seconds for this key
+ *   fn      content generator function for this key
+ *
+ * Return value
+ *   0 indicates success, everything else is an error
+ */
+extern int cache_process(int size, const char *path, const char *key, int ttl,
+			 cache_fill_fn fn);
+
+
+/* List info about all cache entries on stdout */
+extern int cache_ls(const char *path);
+
+/* Print a message to stdout */
+__attribute__((format (printf,1,2)))
+extern void cache_log(const char *format, ...);
+
+extern unsigned long hash_str(const char *str);
+
+#endif /* CGIT_CACHE_H */