Define _POSIX_VERSION correctly when older POSIX versions are selected.

ChangeLog

@@ -1,5 +1,8 @@
 2009-08-23  Ulrich Drepper  <drepper@redhat.com>
 
+	* posix/unistd.h: Define _POSIX_VERSION correctly if older POSIX
+	versions are selected.
+
 	* stdio-common/printf_fp.c: ISO C expects to print the sign of NaN
 	as well.
 	* stdio-common/printf_fphex.c: Likewise.

posix/unistd.h

@@ -30,8 +30,22 @@ __BEGIN_DECLS
 /* These may be used to determine what facilities are present at compile time.
    Their values can be obtained at run time from `sysconf'.  */
 
+#ifdef __USE_XOPEN2K8
 /* POSIX Standard approved as ISO/IEC 9945-1 as of September 2008.  */
-#define	_POSIX_VERSION	200809L
+# define _POSIX_VERSION	200809L
+#elif defined __USE_XOPEN2K
+/* POSIX Standard approved as ISO/IEC 9945-1 as of December 2001.  */
+# define _POSIX_VERSION	200112L
+#elif defined __USE_POSIX199506
+/* POSIX Standard approved as ISO/IEC 9945-1 as of June 1995.  */
+# define _POSIX_VERSION	199506L
+#elif defined __USE_POSIX199309
+/* POSIX Standard approved as ISO/IEC 9945-1 as of September 1993.  */
+# define _POSIX_VERSION	199309L
+#else
+/* POSIX Standard approved as ISO/IEC 9945-1 as of September 1990.  */
+# define _POSIX_VERSION	199009L
+#endif
 
 /* These are not #ifdef __USE_POSIX2 because they are
    in the theoretically application-owned namespace.  */