pingpong: Optimised the endofresp() function

Reworked the pp->endofresp() function so that the conndata, line and
line length are passed down to it just as with Curl_client_write()
rather than each implementation of the function having to query
these values.

Additionally changed the int return type to bool as this is more
representative of the function's usage.

lib/pingpong.c

@@ -395,7 +395,7 @@ CURLcode Curl_pp_readresp(curl_socket_t sockfd,
           if(result)
             return result;
 
-          if(pp->endofresp(pp, code)) {
+          if(pp->endofresp(conn, pp->linestart_resp, perline, code)) {
             /* This is the end of the last line, copy the last line to the
                start of the buffer and zero terminate, for old times sake (and
                krb4)! */