Supply missing move ctor in __bind_r, though this one will eventually be defaulted

llvm-svn: 131408
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 07de7bcaa0051efa1734a89031b804056c05a752
diff --git a/include/functional b/include/functional
index 73c6c59..391a5b6 100644
--- a/include/functional
+++ b/include/functional
@@ -1704,6 +1704,10 @@
 public:
     typedef _R result_type;
 
+    _LIBCPP_INLINE_VISIBILITY
+    __bind_r(__bind_r&& __b)
+        : base(_STD::move(__b)) {}
+
     template <class _G, class ..._BA>
       _LIBCPP_INLINE_VISIBILITY
       explicit __bind_r(_G&& __f, _BA&& ...__bound_args)