Fix x86_64 memrchr namespace (bug 17719).

On x86_64, memrchr (not a standard function) is defined as a strong
symbol, instead of a weak alias of __memrchr as on other
architectures.  This results in linknamespace test failures from the
use of __memrchr from dirname.  (Not a conformance issue because of
the mem* reservation, but contrary to glibc conventions.)  This patch
makes x86_64 follow other architectures by defining memrchr as a weak
alias.

Tested for x86_64 (testsuite, and that disassembly of installed shared
libraries is unchanged by the patch).

	[BZ #17719]
	* sysdeps/x86_64/memrchr.S (memrchr): Rename to __memrchr and
	define as weak alias of __memrchr.
	(__memrchr): Do not define as strong alias of memrchr.
	* conform/Makefile (test-xfail-XPG4/libgen.h/linknamespace):
	Remove variable.
	(test-xfail-UNIX98/libgen.h/linknamespace): Likewise.
	(test-xfail-XOPEN2K/libgen.h/linknamespace): Likewise.
	(test-xfail-XOPEN2K8/libgen.h/linknamespace): Likewise.

ChangeLog

@@ -1,5 +1,15 @@
 2014-12-16  Joseph Myers  <joseph@codesourcery.com>
 
+	[BZ #17719]
+	* sysdeps/x86_64/memrchr.S (memrchr): Rename to __memrchr and
+	define as weak alias of __memrchr.
+	(__memrchr): Do not define as strong alias of memrchr.
+	* conform/Makefile (test-xfail-XPG4/libgen.h/linknamespace):
+	Remove variable.
+	(test-xfail-UNIX98/libgen.h/linknamespace): Likewise.
+	(test-xfail-XOPEN2K/libgen.h/linknamespace): Likewise.
+	(test-xfail-XOPEN2K8/libgen.h/linknamespace): Likewise.
+
 	[BZ #17717]
 	* inet/if_index.c (if_nametoindex): Rename to __if_nametoindex and
 	define as weak alias of __if_nametoindex.  Use libc_hidden_weak.

NEWS

@@ -14,7 +14,7 @@ Version 2.21
   17363, 17370, 17371, 17411, 17460, 17475, 17485, 17501, 17506, 17508,
   17522, 17555, 17570, 17571, 17572, 17573, 17574, 17581, 17582, 17583,
   17584, 17585, 17589, 17594, 17601, 17608, 17616, 17625, 17630, 17633,
-  17634, 17647, 17653, 17657, 17664, 17665, 17668, 17682, 17717.
+  17634, 17647, 17653, 17657, 17664, 17665, 17668, 17682, 17717, 17719.
 
 * CVE-2104-7817 The wordexp function could ignore the WRDE_NOCMD flag
   under certain input conditions resulting in the execution of a shell for

conform/Makefile

@@ -359,7 +359,6 @@ test-xfail-XPG4/ctype.h/linknamespace = yes
 test-xfail-XPG4/fmtmsg.h/linknamespace = yes
 test-xfail-XPG4/fnmatch.h/linknamespace = yes
 test-xfail-XPG4/glob.h/linknamespace = yes
-test-xfail-XPG4/libgen.h/linknamespace = yes
 test-xfail-XPG4/netdb.h/linknamespace = yes
 test-xfail-XPG4/regex.h/linknamespace = yes
 test-xfail-XPG4/search.h/linknamespace = yes
@@ -383,7 +382,6 @@ test-xfail-UNIX98/ctype.h/linknamespace = yes
 test-xfail-UNIX98/fmtmsg.h/linknamespace = yes
 test-xfail-UNIX98/fnmatch.h/linknamespace = yes
 test-xfail-UNIX98/glob.h/linknamespace = yes
-test-xfail-UNIX98/libgen.h/linknamespace = yes
 test-xfail-UNIX98/mqueue.h/linknamespace = yes
 test-xfail-UNIX98/netdb.h/linknamespace = yes
 test-xfail-UNIX98/regex.h/linknamespace = yes
@@ -398,7 +396,6 @@ test-xfail-XOPEN2K/fcntl.h/linknamespace = yes
 test-xfail-XOPEN2K/fmtmsg.h/linknamespace = yes
 test-xfail-XOPEN2K/fnmatch.h/linknamespace = yes
 test-xfail-XOPEN2K/glob.h/linknamespace = yes
-test-xfail-XOPEN2K/libgen.h/linknamespace = yes
 test-xfail-XOPEN2K/mqueue.h/linknamespace = yes
 test-xfail-XOPEN2K/netdb.h/linknamespace = yes
 test-xfail-XOPEN2K/regex.h/linknamespace = yes
@@ -425,7 +422,6 @@ test-xfail-XOPEN2K8/dirent.h/linknamespace = yes
 test-xfail-XOPEN2K8/fcntl.h/linknamespace = yes
 test-xfail-XOPEN2K8/fmtmsg.h/linknamespace = yes
 test-xfail-XOPEN2K8/grp.h/linknamespace = yes
-test-xfail-XOPEN2K8/libgen.h/linknamespace = yes
 test-xfail-XOPEN2K8/mqueue.h/linknamespace = yes
 test-xfail-XOPEN2K8/netdb.h/linknamespace = yes
 test-xfail-XOPEN2K8/pwd.h/linknamespace = yes

sysdeps/x86_64/memrchr.S

@@ -21,7 +21,7 @@
 #include <sysdep.h>
 
 	.text
-ENTRY (memrchr)
+ENTRY (__memrchr)
 	movd	%rsi, %xmm1
 
 	sub	$16, %rdx
@@ -378,5 +378,5 @@ L(length_less16_part2_return):
 	lea	16(%rax, %rdi), %rax
 	ret
 
-END (memrchr)
-strong_alias (memrchr, __memrchr)
+END (__memrchr)
+weak_alias (__memrchr, memrchr)