Remove MG_ENABLE_STDIO and cleanup

src/http.h

@@ -23,6 +23,7 @@ struct mg_http_serve_opts {
   const char *root_dir;       // Web root directory, must be non-NULL
   const char *ssi_pattern;    // SSI file name pattern, e.g. #.shtml
   const char *extra_headers;  // Extra HTTP headers to add in responses
+  bool use_packed_fs;         // Serve files embedded into binary
 };
 
 // Parameter for mg_http_next_multipart