save 8 bytes in http_parser structure

nread can never be larger than HTTP_MAX_HEADER_SIZE

http_parser.h

@@ -100,14 +100,13 @@ enum http_parser_type { HTTP_REQUEST, HTTP_RESPONSE, HTTP_BOTH };
 
 struct http_parser {
   /** PRIVATE **/
-  unsigned char type;
+  unsigned char type : 2;
+  unsigned char flags : 6;
   unsigned char state;
   unsigned char header_state;
   unsigned char index;
 
-  char flags;
+  uint32_t nread;
-
-  uint64_t nread;
   int64_t content_length;
 
   /** READ-ONLY **/