Add struct mg_http_serve_opts::extra_headers

src/http.h

@@ -23,8 +23,9 @@ struct mg_http_message {
 
 // Parameter for mg_http_serve_dir()
 struct mg_http_serve_opts {
-  const char *root_dir;     // Web root directory, must be non-NULL
-  const char *ssi_pattern;  // SSI filename pattern, e.g. #.shtml
+  const char *root_dir;       // Web root directory, must be non-NULL
+  const char *ssi_pattern;    // SSI filename pattern, e.g. #.shtml
+  const char *extra_headers;  // Extra HTTP headers to add in responses
 };
 
 int mg_http_parse(const char *s, size_t len, struct mg_http_message *);