Put xtables.c into its own library, libxtables.so

iproute2's tc's m_ipt.c poses as a pseudo-iptables program to make
use of the info structure composition of iptables extensions.
Since tc would have to clone a lot of code, xtables.c is put into
its own shared library and should not be relied upon by any other
programs.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/xtables.pc.in b/xtables.pc.in
new file mode 100644
index 0000000..7246d7b
--- /dev/null
+++ b/xtables.pc.in
@@ -0,0 +1,11 @@
+
+prefix=@prefix@
+exec_prefix=@exec_prefix@
+libdir=@libdir@
+xtlibdir=@xtlibdir@
+includedir=@includedir@
+
+Name:		xtables
+Description:	Shared Xtables code for extensions and iproute2
+Version:	@PACKAGE_VERSION@
+Libs:		-lxtables