libstdc++: Include <bits/stl_iterator.h> in <bits/alloc_traits.h>

libstdc++-v3/ChangeLog:

	* include/bits/alloc_traits.h: Include <bits/stl_iterator.h> for
	__make_move_if_noexcept_iterator.

Author: jwakely

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

@@ -38,6 +38,9 @@
 # if _GLIBCXX_HOSTED
 #  include <bits/allocator.h>
 # endif
+# if __cpp_exceptions
+#  include <bits/stl_iterator.h> // __make_move_if_noexcept_iterator
+# endif
 #endif
 
 namespace std _GLIBCXX_VISIBILITY(default)