Partial backport of:

commit 17c199ee92e4ca8a34a47c42924608a25a444eb2
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Wed Jun 17 20:08:22 2015 +0000

    Fix gethostbyaddr in6addr_any, in6addr_loopback namespace (bug 18532).

The conform/Makefile changes have been omitted because glibc 2.17 did
not have linknamespace tests.

diff --git a/include/netinet/in.h b/include/netinet/in.h
index 6fb5c86de999ba82..5e377469e782a5b1 100644
--- a/include/netinet/in.h
+++ b/include/netinet/in.h
@@ -5,7 +5,11 @@
 #ifndef _ISOMAC
 libc_hidden_proto (bindresvport)
 libc_hidden_proto (in6addr_loopback)
+extern __typeof (in6addr_loopback) __in6addr_loopback;
+libc_hidden_proto (__in6addr_loopback)
 libc_hidden_proto (in6addr_any)
+extern __typeof (in6addr_any) __in6addr_any;
+libc_hidden_proto (__in6addr_any)
 #endif
 
 #endif
diff --git a/inet/gethstbyad_r.c b/inet/gethstbyad_r.c
index d8e4988a312a0799..5ae854b4f91e72ad 100644
--- a/inet/gethstbyad_r.c
+++ b/inet/gethstbyad_r.c
@@ -32,7 +32,7 @@
    be performed.  */
 #define PREPROCESS \
   if (len == sizeof (struct in6_addr)					      \
-      && __builtin_expect (memcmp (&in6addr_any, addr,			      \
+      && __builtin_expect (memcmp (&__in6addr_any, addr,		      \
 				   sizeof (struct in6_addr)), 1) == 0)	      \
     {									      \
       *h_errnop = HOST_NOT_FOUND;					      \
diff --git a/inet/in6_addr.c b/inet/in6_addr.c
index 558b375e46dc62dc..03fbb85803e3d0b7 100644
--- a/inet/in6_addr.c
+++ b/inet/in6_addr.c
@@ -18,9 +18,13 @@
 
 #include <netinet/in.h>
 
-const struct in6_addr in6addr_any =
+const struct in6_addr __in6addr_any =
 { { { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 } } };
-libc_hidden_data_def (in6addr_any)
-const struct in6_addr in6addr_loopback =
+libc_hidden_data_def (__in6addr_any)
+weak_alias (__in6addr_any, in6addr_any)
+libc_hidden_data_weak (in6addr_any)
+const struct in6_addr __in6addr_loopback =
 { { { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1 } } };
-libc_hidden_data_def (in6addr_loopback)
+libc_hidden_data_def (__in6addr_loopback)
+weak_alias (__in6addr_loopback, in6addr_loopback)
+libc_hidden_data_weak (in6addr_loopback)