[PATCH] ipv6: Provide definitions for GNU libc 2.8 and later

[Thierry Reding <thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

From: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>

Starting with GNU libc 2.8 and later, the definitions of the in6_pktinfo
and ip6_mtuinfo structures is guarded by __USE_GNU. Make sure to provide
the structures in the linux/ipv6.h when building against GNU libc 2.8 or
later and __USE_GNU is undefined to avoid breaking build issues.

One example where such failure to build can be observed is dhcpcd 6.6.7.

Signed-off-by: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
---
This is based on next-20150122.

 include/uapi/linux/libc-compat.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/uapi/linux/libc-compat.h b/include/uapi/linux/libc-compat.h
index fa673e9cc040..40bd54df06e3 100644
--- a/include/uapi/linux/libc-compat.h
+++ b/include/uapi/linux/libc-compat.h
@@ -70,8 +70,17 @@
 #define __UAPI_DEF_IPV6_MREQ		0
 #define __UAPI_DEF_IPPROTO_V6		0
 #define __UAPI_DEF_IPV6_OPTIONS		0
+/*
+ * The GNU C library 2.8 and later define the in6_pktinfo and ip6_mtuinfo
+ * structures only for __USE_GNU.
+ */
+#if __GLIBC_PREREQ(2, 8) && !defined(__USE_GNU)
+#define __UAPI_DEF_IN6_PKTINFO		1
+#define __UAPI_DEF_IP6_MTUINFO		1
+#else
 #define __UAPI_DEF_IN6_PKTINFO		0
 #define __UAPI_DEF_IP6_MTUINFO		0
+#endif
 
 #else
 
-- 
2.1.3