Distinguish older version of iptables by version number.

Distinguish isn't by presence or absence of pkgconfig (newer versions
are supposed to have it), but by version number (too).
This check is still inexact, though.

configure

@@ -192,7 +192,8 @@ iptables_try_pkgconfig() {
     PKGVER=`pkg-config --modversion xtables 2>/dev/null`
     PKGINC=`pkg-config --cflags xtables`
     PKGLIB=`pkg-config --variable=xtlibdir xtables`
-  else
+  elif [[ "$IPTVER" =~ ^1\.3 ]]; then
+    echo "! This version of iptables ($IPTVER) will be treated as old version."
     # Newer versions of iptables should not have -I/kernel/include!
     # So I assume that newer version will have correct pkg-config set up
     # and if not, then it's older who need it.