build: remove support for Linux 4.8

configure.ac

@@ -59,7 +59,7 @@ if test -n "$kbuilddir"; then
 		echo "$kmajor.$kminor.$kmicro.$kstable in $kbuilddir";
 		if test "$kmajor" -gt 4 -o "$kmajor" -eq 4 -a "$kminor" -gt 12; then
 			echo "WARNING: That kernel version is not officially supported yet. Continue at own luck.";
-		elif test "$kmajor" -eq 4 -a "$kminor" -le 7; then
+		elif test "$kmajor" -eq 4 -a "$kminor" -le 8; then
 			echo "WARNING: That kernel version is not officially supported.";
 		elif test "$kmajor" -eq 4 -a "$kminor" -le 10; then
 			:;

doc/changelog.txt

@@ -4,7 +4,7 @@ HEAD
 Enhancements:
 - support for Linux up to 4.15
 Changes:
-- remove support for Linux 3.7--4.7
+- remove support for Linux 3.7--4.8
 
 
 v2.14 (2017-11-22)

extensions/compat_xtables.h

@@ -8,8 +8,8 @@
 
 #define DEBUGP Use__pr_debug__instead
 
-#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 8, 0)
-#	warning Kernels below 4.8 not supported.
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 9, 0)
+#	warning Kernels below 4.9 not supported.
 #endif
 
 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)

extensions/xt_LOGMARK.c

@@ -64,12 +64,7 @@ static void logmark_ct(const struct nf_conn *ct, enum ip_conntrack_info ctinfo)
 		printk("%s""CONFIRMED", prev ? "," : "");
 		prev = true;
 	}
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(4,9,0)
 	printk(" lifetime=%lus", nf_ct_expires(ct) / HZ);
-#else
-	printk(" lifetime=%lus",
-	       (jiffies - ct->timeout.expires) / HZ);
-#endif
 }
 
 static unsigned int