Move the default template arguments into the forward declarations for the container adapters: stack and queue. References PR#22605.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@229708 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/queue b/include/queue
index bdfd706..6f49c87 100644
--- a/include/queue
+++ b/include/queue
@@ -177,7 +177,7 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-template <class _Tp, class _Container> class _LIBCPP_TYPE_VIS_ONLY queue;
+template <class _Tp, class _Container = deque<_Tp> > class _LIBCPP_TYPE_VIS_ONLY queue;
 
 template <class _Tp, class _Container>
 _LIBCPP_INLINE_VISIBILITY
@@ -189,7 +189,7 @@
 bool
 operator< (const queue<_Tp, _Container>& __x,const queue<_Tp, _Container>& __y);
 
-template <class _Tp, class _Container = deque<_Tp> >
+template <class _Tp, class _Container /*= deque<_Tp>*/>
 class _LIBCPP_TYPE_VIS_ONLY queue
 {
 public: