Fix display/loop issue with Disconnect-after-file-transfer prompt

As reported by WitNik, on 32-bit rPi builds, the loop would not
terminate and display transfer count down values after hitting 'H'
to hang-up.

src/sbbs3/download.cpp

@@ -264,7 +264,8 @@ int sbbs_t::protocol(prot_t* prot, enum XFER_TYPE type
 /****************************************************************************/
 void sbbs_t::autohangup()
 {
-    char	a,c,k;
+    int		a,c;
+	char	k;
 	char 	tmp[512];
 
 	if(online!=ON_REMOTE)