Increase the read buffer size in network processing for extra speed.

[originally from svn r1047]

winnet.c

@@ -621,7 +621,7 @@ static void sk_tcp_write_oob(Socket sock, char *buf, int len) {
 int select_result(WPARAM wParam, LPARAM lParam) {
     int ret, open;
     DWORD err;
-    char buf[BUFFER_GRANULE];
+    char buf[20480];		       /* nice big buffer for plenty of speed */
     Actual_Socket s;
     u_long atmark;