Fix const correctness bug in __move_assign.  Found and fixed by Ion Gaztañaga.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@139032 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/deque b/include/deque
index 69682a1..87cbe59 100644
--- a/include/deque
+++ b/include/deque
@@ -977,14 +977,14 @@
 
 private:
     _LIBCPP_INLINE_VISIBILITY
-    void __move_assign_alloc(const __deque_base& __c, true_type)
+    void __move_assign_alloc(__deque_base& __c, true_type)
         _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
         {
             __alloc() = _VSTD::move(__c.__alloc());
         }
 
     _LIBCPP_INLINE_VISIBILITY
-    void __move_assign_alloc(const __deque_base& __c, false_type) _NOEXCEPT
+    void __move_assign_alloc(__deque_base& __c, false_type) _NOEXCEPT
         {}
 
     _LIBCPP_INLINE_VISIBILITY