Undefine attribute_hidden to fix benchtests

Add an undefine of attribute_hidden since it may be defined in some cases
(it must be defined since it is used by some hp-timing configurations).

	* benchtests/bench-timing.h (attribute_hidden): Undefine.

ChangeLog

@@ -1,3 +1,7 @@
+2018-03-19  Wilco Dijkstra  <wdijkstr@arm.com>
+
+	* benchtests/bench-timing.h (attribute_hidden): Undefine.
+
 2018-03-18  Richard Braun  <rbraun@sceen.net>
 
 	* sysdeps/mach/hurd/i386/tls.h (_hurd_tls_init): Use a temporary

benchtests/bench-timing.h

@@ -16,6 +16,7 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#undef attribute_hidden
 #define attribute_hidden
 #include <hp-timing.h>
 #include <stdint.h>