Fixes to enable building with latest autoconf and automake

JL 09/02/10

Index: libpcap-0.9.3/configure.in
===================================================================
--- libpcap-0.9.3.orig/configure.in	2005-07-07 07:56:03.000000000 +0100
+++ libpcap-0.9.3/configure.in	2010-02-09 15:19:40.529662003 +0000
@@ -11,6 +11,7 @@
 AC_INIT(pcap.c)
 
 AC_CANONICAL_SYSTEM
+AC_PROG_CC
 
 AC_LBL_C_INIT(V_CCOPT, V_INCLS, V_LIBS)
 AC_LBL_C_INLINE