fix warnings in event.c when building for win32-64

fix warnings in event.c when building for win32-64

When compiling for 64-bit Windows gcc warns about

  "cast from pointer to integer of different size"

on two occasions in file event.c, due to invalid casting.
This patch removes the type casts and uses the correct
format specifier instead.

Signed-off-by: Heiko Hund <heiko.hund@sophos.com>
Acked-by: James Yonan <james@openvpn.net>
URL: http://article.gmane.org/gmane.network.openvpn.devel/4979
Signed-off-by: David Sommerseth <davids@redhat.com>