slirp: Fix type casts and format strings in debug code

Casting pointers to long won't work on 64 bit Windows.
It is not needed with the right format strings.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Jason Wang <jasowang@redhat.com>
diff --git a/slirp/if.c b/slirp/if.c
index fb7acf8..8325a2a 100644
--- a/slirp/if.c
+++ b/slirp/if.c
@@ -53,8 +53,8 @@
 	int on_fastq = 1;
 
 	DEBUG_CALL("if_output");
-	DEBUG_ARG("so = %lx", (long)so);
-	DEBUG_ARG("ifm = %lx", (long)ifm);
+	DEBUG_ARG("so = %p", so);
+	DEBUG_ARG("ifm = %p", ifm);
 
 	/*
 	 * First remove the mbuf from m_usedlist,