compat: drop Ubuntu 14.04

It's been over a year since we announced sunsetting this.

Link: https://lore.kernel.org/wireguard/CAHmME9rckipsdZYW+LA=x6wCMybdFFA+VqoogFXnR=kHYiCteg@mail.gmail.com/T
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

Author: zx2c4

src/compat/compat.h

@@ -22,9 +22,7 @@
 #endif
 #endif
 #ifdef UTS_UBUNTU_RELEASE_ABI
-#if LINUX_VERSION_CODE == KERNEL_VERSION(3, 13, 11)
-#define ISUBUNTU1404
-#elif LINUX_VERSION_CODE < KERNEL_VERSION(4, 5, 0) && LINUX_VERSION_CODE >= KERNEL_VERSION(4, 4, 0)
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 5, 0) && LINUX_VERSION_CODE >= KERNEL_VERSION(4, 4, 0)
 #define ISUBUNTU1604
 #elif LINUX_VERSION_CODE < KERNEL_VERSION(4, 16, 0) && LINUX_VERSION_CODE >= KERNEL_VERSION(4, 15, 0)
 #define ISUBUNTU1804
@@ -219,7 +217,7 @@ static inline void skb_scrub_packet(struct sk_buff *skb, bool xnet)
 #define skb_scrub_packet(a, b) skb_scrub_packet(a)
 #endif
 
-#if ((LINUX_VERSION_CODE < KERNEL_VERSION(3, 14, 0) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 13, 0)) || LINUX_VERSION_CODE < KERNEL_VERSION(3, 12, 63) || defined(ISUBUNTU1404)) && !defined(ISRHEL7)
+#if ((LINUX_VERSION_CODE < KERNEL_VERSION(3, 14, 0) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 13, 0)) || LINUX_VERSION_CODE < KERNEL_VERSION(3, 12, 63)) && !defined(ISRHEL7)
 #include <linux/random.h>
 static inline u32 __compat_prandom_u32_max(u32 ep_ro)
 {
@@ -268,7 +266,7 @@ static inline u32 __compat_prandom_u32_max(u32 ep_ro)
 #endif
 #endif
 
-#if (LINUX_VERSION_CODE < KERNEL_VERSION(3, 17, 3) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 17, 0)) || (LINUX_VERSION_CODE < KERNEL_VERSION(3, 16, 35) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 15, 0)) || (LINUX_VERSION_CODE < KERNEL_VERSION(3, 14, 24) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 13, 0) && !defined(ISUBUNTU1404)) || (LINUX_VERSION_CODE < KERNEL_VERSION(3, 12, 33) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 11, 0)) || (LINUX_VERSION_CODE < KERNEL_VERSION(3, 10, 60) && !defined(ISRHEL7))
+#if (LINUX_VERSION_CODE < KERNEL_VERSION(3, 17, 3) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 17, 0)) || (LINUX_VERSION_CODE < KERNEL_VERSION(3, 16, 35) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 15, 0)) || (LINUX_VERSION_CODE < KERNEL_VERSION(3, 14, 24) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 13, 0)) || (LINUX_VERSION_CODE < KERNEL_VERSION(3, 12, 33) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 11, 0)) || (LINUX_VERSION_CODE < KERNEL_VERSION(3, 10, 60) && !defined(ISRHEL7))
 static inline void memzero_explicit(void *s, size_t count)
 {
 	memset(s, 0, count);
@@ -502,7 +500,7 @@ static inline void *__compat_kvzalloc(size_t size, gfp_t flags)
 #define kvzalloc __compat_kvzalloc
 #endif
 
-#if ((LINUX_VERSION_CODE < KERNEL_VERSION(3, 15, 0) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 13, 0)) || LINUX_VERSION_CODE < KERNEL_VERSION(3, 12, 41)) && !defined(ISUBUNTU1404)
+#if ((LINUX_VERSION_CODE < KERNEL_VERSION(3, 15, 0) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 13, 0)) || LINUX_VERSION_CODE < KERNEL_VERSION(3, 12, 41))
 #include <linux/vmalloc.h>
 #include <linux/mm.h>
 static inline void __compat_kvfree(const void *addr)