[v3][committed] Add dg-require-time to variadic_construct.cc

[Richard Sandiford]

The recently-added ext/throw_allocator/variadic_construct.cc test
was failing on targets without time().  The other run-time tests in
that directory all dg-require-time, so I made this test do the same.
Tested on x86_64-linux-gnu and mipsisa64-elf and applied as obvious.

Richard


	* testsuite/ext/throw_allocator/variadic_construct.cc: Add
	dg-require-time.

Index: libstdc++-v3/testsuite/ext/throw_allocator/variadic_construct.cc
===================================================================
--- libstdc++-v3/testsuite/ext/throw_allocator/variadic_construct.cc	(revision 130297)
+++ libstdc++-v3/testsuite/ext/throw_allocator/variadic_construct.cc	(working copy)
@@ -20,6 +20,8 @@
 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
 // USA.
 
+// { dg-require-time "" }
+
 #include <ext/throw_allocator.h>
 #include <utility>
 #include <testsuite_hooks.h>