libxtables: prefix/order - program_name

Split XTABLES_VERSION into xtables and iptables, and encode the
xtables soversion into the extensions instead. This makes it possible
to upgrade iptables without having to recompile 3rd-party extensions
(if the libxtables version matches, of course).

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
diff --git a/iptables-standalone.c b/iptables-standalone.c
index c06b286..9190873 100644
--- a/iptables-standalone.c
+++ b/iptables-standalone.c
@@ -51,8 +51,9 @@
 	struct iptc_handle *handle = NULL;
 
 	program_name = "iptables";
-	program_version = XTABLES_VERSION;
+	program_version = IPTABLES_VERSION;
 
+	xtables_program_name = program_name;
 	xtables_init();
 #ifdef NO_SHARED_LIBS
 	init_extensions();