urldata: reduce three type-members from int to uchar

- timecondition
 - proxytype
 - method

... previously used their enum type in the struct, which made them
unnecesarily large.

Closes #9105

lib/urldata.h

@@ -1732,10 +1732,10 @@ struct UserDefined {
                                      DNS cache */
   struct curl_slist *connect_to; /* list of host:port mappings to override
                                     the hostname and port to connect to */
-  curl_TimeCond timecondition; /* kind of time/date comparison */
-  curl_proxytype proxytype; /* what kind of proxy that is in use */
   time_t timevalue;       /* what time to compare with */
-  Curl_HttpReq method;   /* what kind of HTTP request (if any) is this */
+  unsigned char timecondition; /* kind of time comparison: curl_TimeCond */
+  unsigned char proxytype; /* what kind of proxy: curl_proxytype */
+  unsigned char method;   /* what kind of HTTP request: Curl_HttpReq */
   unsigned char httpwant; /* when non-zero, a specific HTTP version requested
                              to be used in the library's request(s) */
   struct ssl_config_data ssl;  /* user defined SSL stuff */