netfilter: Combine ipt_TTL and ip6t_HL source

Suggested by: James King <t.james.king@gmail.com>

Similarly to commit c9fd49680954714473d6cbd2546d6ff120f96840, merge
TTL and HL. Since HL does not depend on any IPv6-specific function,
no new module dependencies would arise.

With slight adjustments to the Kconfig help text.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index c2bac9c..d99f29b 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -357,6 +357,21 @@
 
 	  To compile it as a module, choose M here.  If unsure, say N.
 
+config NETFILTER_XT_TARGET_HL
+	tristate '"HL" hoplimit target support'
+	depends on IP_NF_MANGLE || IP6_NF_MANGLE
+	depends on NETFILTER_ADVANCED
+	---help---
+	This option adds the "HL" (for IPv6) and "TTL" (for IPv4)
+	targets, which enable the user to change the
+	hoplimit/time-to-live value of the IP header.
+
+	While it is safe to decrement the hoplimit/TTL value, the
+	modules also allow to increment and set the hoplimit value of
+	the header to arbitrary values. This is EXTREMELY DANGEROUS
+	since you can easily create immortal packets that loop
+	forever on the network.
+
 config NETFILTER_XT_TARGET_MARK
 	tristate '"MARK" target support'
 	default m if NETFILTER_ADVANCED=n