parse_remote_port: fix ;type= URL suffix over HTTP proxy

Test 563 is enabled now and verifies that the combo FTP type=A URL,
CURLOPT_PORT set and proxy work fine. As a bonus I managed to remove the
somewhat odd FTP check in parse_remote_port() and instead converted it
to a better and more generic 'slash_removed' struct field. Checking the
->protocol field isn't right since when an FTP:// URL is sent over a
HTTP proxy, the protocol is HTTP but the URL was handled by the FTP code
and thus slash_removed is set TRUE for this case.

lib/ftp.c

@@ -4178,6 +4178,7 @@ static CURLcode ftp_setup_connection(struct connectdata * conn)
   }
 
   data->state.path++;   /* don't include the initial slash */
+  data->state.slash_removed = TRUE; /* we've skipped the slash */
 
   /* FTP URLs support an extension like ";type=<typecode>" that
    * we'll try to get now! */
@@ -4189,6 +4190,7 @@ static CURLcode ftp_setup_connection(struct connectdata * conn)
   if(type) {
     *type = 0;                     /* it was in the middle of the hostname */
     command = Curl_raw_toupper(type[6]);
+    conn->bits.type_set = TRUE;
 
     switch (command) {
     case 'A': /* ASCII mode */