reduce http_parser from 60 bytes to 48 bytes

This is mostly done by using sized types instead of enums, and
reordering fields to allow better packing.

I also moved the 'upgrade' field out of the PRIVATE section and into
the READ-ONLY section, as I believe that it is supposed to be
non-private.

http_parser.h

@@ -94,17 +94,10 @@ enum http_parser_type { HTTP_REQUEST, HTTP_RESPONSE, HTTP_BOTH };
 
 struct http_parser {
   /** PRIVATE **/
-  enum http_parser_type type;
-  unsigned short state;
-  unsigned short header_state;
-  size_t index;
-
-  /* 1 = Upgrade header was present and the parser has exited because of that.
-   * 0 = No upgrade header present.
-   * Should be checked when http_parser_execute() returns in addition to
-   * error checking.
-   */
-  unsigned short upgrade;
+  unsigned char type;
+  unsigned char state;
+  unsigned char header_state;
+  unsigned char index;
 
   char flags;
 
@@ -122,11 +115,18 @@ struct http_parser {
 
   /** READ-ONLY **/
   unsigned short status_code; /* responses only */
-  enum http_method method;    /* requests only */
+  unsigned short method;    /* requests only */
   unsigned short http_major;
   unsigned short http_minor;
   char buffer[HTTP_PARSER_MAX_METHOD_LEN];
 
+  /* 1 = Upgrade header was present and the parser has exited because of that.
+   * 0 = No upgrade header present.
+   * Should be checked when http_parser_execute() returns in addition to
+   * error checking.
+   */
+  char upgrade;
+
   /** PUBLIC **/
   void *data; /* A pointer to get hook to the "connection" or "socket" object */
 };