commit 1c1e7fb65828c99d6e0f0f3857089b559a0c8189
Author: Carlos O'Donell <carlos@redhat.com>
Date:   Thu Jun 2 23:30:11 2016 -0400

    Fix macro API for __USE_KERNEL_IPV6_DEFS.
    
    The use of __USE_KERNEL_IPV6_DEFS with ifndef is bad
    practice per: https://sourceware.org/glibc/wiki/Wundef.
    This change moves it to use 'if' and always define the
    macro.
    
    Please note that this is not the only problem with this
    code. I have a series of fixes after this one to resolve
    breakage with this code and add regression tests for it
    via compile-only source testing (to be discussed in another
    thread).
    
    Unfortunately __USE_KERNEL_XATTR_DEFS is set by the kernel
    and not glibc, and uses 'define', so we can't fix that yet.

Index: glibc-2.17-c758a686/inet/netinet/in.h
===================================================================
--- glibc-2.17-c758a686.orig/inet/netinet/in.h
+++ glibc-2.17-c758a686/inet/netinet/in.h
@@ -91,10 +91,10 @@ enum
     IPPROTO_MAX
   };
 
-/* If __USER_KERNEL_IPV6_DEFS is defined then the user has included the kernel
+/* If __USE_KERNEL_IPV6_DEFS is 1 then the user has included the kernel
    network headers first and we should use those ABI-identical definitions
-   instead of our own.  */
-#ifndef __USE_KERNEL_IPV6_DEFS
+   instead of our own, otherwise 0.  */
+#if !__USE_KERNEL_IPV6_DEFS
 enum
   {
     IPPROTO_HOPOPTS = 0,   /* IPv6 Hop-by-Hop options.  */
@@ -205,7 +205,7 @@ enum
 #define INADDR_ALLRTRS_GROUP    ((in_addr_t) 0xe0000002) /* 224.0.0.2 */
 #define INADDR_MAX_LOCAL_GROUP  ((in_addr_t) 0xe00000ff) /* 224.0.0.255 */
 
-#ifndef __USE_KERNEL_IPV6_DEFS
+#if !__USE_KERNEL_IPV6_DEFS
 /* IPv6 address */
 struct in6_addr
   {
@@ -248,7 +248,7 @@ struct sockaddr_in
 			   sizeof (struct in_addr)];
   };
 
-#ifndef __USE_KERNEL_IPV6_DEFS
+#if !__USE_KERNEL_IPV6_DEFS
 /* Ditto, for IPv6.  */
 struct sockaddr_in6
   {
@@ -284,7 +284,7 @@ struct ip_mreq_source
   };
 #endif
 
-#ifndef __USE_KERNEL_IPV6_DEFS
+#if !__USE_KERNEL_IPV6_DEFS
 /* Likewise, for IPv6.  */
 struct ipv6_mreq
   {
@@ -531,7 +531,7 @@ extern int bindresvport6 (int __sockfd,
 #ifdef __USE_GNU
 struct cmsghdr;			/* Forward declaration.  */
 
-#ifndef __USE_KERNEL_IPV6_DEFS
+#if !__USE_KERNEL_IPV6_DEFS
 /* IPv6 packet information.  */
 struct in6_pktinfo
   {
Index: glibc-2.17-c758a686/sysdeps/unix/sysv/linux/bits/in.h
===================================================================
--- glibc-2.17-c758a686.orig/sysdeps/unix/sysv/linux/bits/in.h
+++ glibc-2.17-c758a686/sysdeps/unix/sysv/linux/bits/in.h
@@ -30,7 +30,9 @@
 /* This is not quite the same API since the kernel always defines s6_addr16 and
    s6_addr32. This is not a violation of POSIX since POSIX says "at least the
    following member" and that holds true.  */
-# define __USE_KERNEL_IPV6_DEFS
+# define __USE_KERNEL_IPV6_DEFS 1
+#else
+# define __USE_KERNEL_IPV6_DEFS 0
 #endif
 
 /* Options for use with `getsockopt' and `setsockopt' at the IP level.