Fix h_errno namespace (bug 18520)

[Carlos O'Donell]

On 06/11/2015 05:33 PM, Joseph Myers wrote:
> The 2008 edition of POSIX removed h_errno, but some functions still
> bring in references to the h_errno external symbol.  As this symbol is
> not a part of the public ABI (only __h_errno_location is), this patch
> fixes this by renaming the GLIBC_PRIVATE TLS symbol to __h_errno.
> 
> Tested for x86_64 and x86 (testsuite, and comparison of installed
> shared libraries).  Disassembly of all shared libraries using h_errno
> changes because of the renaming (and changes to associated TLS / GOT
> offsets in some cases); disassembly of libpthread on x86_64 changes
> more substantially because the enlargement of .dynsym affects
> subsequent addresses.
> 
> 2015-06-11  Joseph Myers  <joseph@codesourcery.com>
> 
> 	[BZ #18520]
> 	* inet/herrno.c (h_errno): Rename to __h_errno.
> 	(__libc_h_errno): Define as alias of __h_errno not h_errno.
> 	* include/netdb.h [IS_IN_LIB && !IS_IN (libc)] (h_errno): Define
> 	to __h_errno instead of h_errno.
> 	* nptl/herrno.c (h_errno): Rename to __h_errno.
> 	(__h_errno_location): Refer to __h_errno not h_errno.
> 	* resolv/Versions (h_errno): Rename to __h_errno.
> 	* conform/Makefile (test-xfail-XOPEN2K8/grp.h/linknamespace):
> 	Remove variable.
> 	(test-xfail-XOPEN2K8/pwd.h/linknamespace): Likewise.
> 

Looks good to me.

c.