Fix sys/stat.h fchmod namespace (bug 20073)

[Joseph Myers]

sys/stat.h declares fchmod if __USE_POSIX (i.e. POSIX.1:1990).  But it
was actually added in 1993 and also in XPG4.  This patch changes the
conditions to the correct __USE_POSIX199309 || __USE_XOPEN_EXTENDED.

Tested for x86_64 and x86 (testsuite, and that installed shared
libraries are unchanged by the patch).

2016-05-10  Joseph Myers  <joseph@codesourcery.com>

	[BZ #20073]
	* io/sys/stat.h (fchmod): Declare for
	[__USE_POSIX199309 || __USE_XOPEN_EXTENDED], not [__USE_POSIX].
	* conform/Makefile (test-xfail-XPG3/sys/stat.h/conform): Remove
	variable.

diff --git a/conform/Makefile b/conform/Makefile
index c4412ef..6291ca9 100644
--- a/conform/Makefile
+++ b/conform/Makefile
@@ -171,7 +171,6 @@ test-xfail-XPG3/search.h/conform = yes
 test-xfail-XPG3/signal.h/conform = yes
 test-xfail-XPG3/stdlib.h/conform = yes
 test-xfail-XPG3/string.h/conform = yes
-test-xfail-XPG3/sys/stat.h/conform = yes
 test-xfail-XPG3/sys/wait.h/conform = yes
 test-xfail-XPG3/termios.h/conform = yes
 test-xfail-XPG3/time.h/conform = yes
diff --git a/io/sys/stat.h b/io/sys/stat.h
index bf63882..416d564 100644
--- a/io/sys/stat.h
+++ b/io/sys/stat.h
@@ -292,7 +292,7 @@ extern int lchmod (const char *__file, __mode_t __mode)
 #endif
 
 /* Set file access permissions of the file FD is open on to MODE.  */
-#ifdef __USE_POSIX
+#if defined __USE_POSIX199309 || defined __USE_XOPEN_EXTENDED
 extern int fchmod (int __fd, __mode_t __mode) __THROW;
 #endif
 

-- 
Joseph S. Myers
joseph@codesourcery.com