Remove redundant #if conditional

The whole file is guarded by the same check already.

	* include/bits/alloc_traits.h: Remove redundant preprocessor
	condition.

From-SVN: r262359

libstdc++-v3/ChangeLog

+2018-07-03  Jonathan Wakely  <jwakely@redhat.com>
+
+	* include/bits/alloc_traits.h: Remove redundant preprocessor
+	condition.
+
 2018-07-03  François Dumont  <fdumont@gcc.gnu.org>
 
 	* include/bits/stl_algobase.h (__niter_wrap): New.

libstdc++-v3/include/bits/alloc_traits.h

@@ -598,7 +598,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     : is_copy_constructible<_Tp>
     { };
 
-#if __cplusplus >= 201103L
   // Trait to detect Allocator-like types.
   template<typename _Alloc, typename = void>
     struct __is_allocator : false_type { };
@@ -612,10 +611,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   template<typename _Alloc>
     using _RequireAllocator
       = typename enable_if<__is_allocator<_Alloc>::value, _Alloc>::type;
-#endif
 
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace std
-
-#endif
-#endif
+#endif // C++11
+#endif // _ALLOC_TRAITS_H