http: use boolean for version

The version can only ever be 1 (meaning 1.1, the default) or 0
(meaning 1.0, the fallback).

This plugin does not support version 2.0 or obsolete version 0.9.

modules/access/http.c

@@ -148,11 +148,11 @@ struct access_sys_t
     /* */
     int        i_code;
     const char *psz_protocol;
-    int        i_version;
 
     char       *psz_mime;
     char       *psz_pragma;
     char       *psz_location;
+    bool i_version;
     bool b_mms;
     bool b_icecast;
 #ifdef HAVE_ZLIB_H