containers/netns: Add IFLA_NET_NS_PID configure check

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
diff --git a/configure.ac b/configure.ac
index 0198ac7..ecea070 100644
--- a/configure.ac
+++ b/configure.ac
@@ -177,5 +177,6 @@
 LTP_CHECK_IOVEC
 LTP_CHECK_KEYCTL
 LTP_CHECK_LINUXRANDOM
+LTP_CHECK_IF_LINK
 
 AC_OUTPUT