osmo_pcap_client: Start with the framework for the pcap client

This is just the normal skeleton for the osmocom code.
diff --git a/configure.ac b/configure.ac
index b57b3dd..51669ec 100644
--- a/configure.ac
+++ b/configure.ac
@@ -50,6 +50,7 @@
    AC_SUBST([COVERAGE_LDFLAGS])
 fi
 
+AM_CONFIG_HEADER(osmopcapconfig.h)
 
 dnl Generate the output
 AC_OUTPUT(