Restrict optimized __pad_and_output implementation detail to desired releases.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@167980 91177308-0d34-0410-b5e6-96231b3b80d8

include/iterator

@@ -317,6 +317,10 @@ template <class T, size_t N> T* end(T (&array)[N]);
 #include <type_traits>
 #include <cstddef>
 #include <iosfwd>
+#if __APPLE__
+#include <Availability.h>
+#endif
+
 #ifdef _LIBCPP_DEBUG
 #include <cassert>
 #endif
@@ -882,6 +886,10 @@ public:
     _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator++(int) {return *this;}
     _LIBCPP_INLINE_VISIBILITY bool failed() const _NOEXCEPT {return __sbuf_ == 0;}
 
+#if !defined(__APPLE__) || \
+    (defined(__MAC_OS_X_VERSION_MIN_REQUIRED) && __MAC_OS_X_VERSION_MIN_REQUIRED > __MAC_10_8) || \
+    (defined(__IPHONE_OS_VERSION_MIN_REQUIRED) && __IPHONE_OS_VERSION_MIN_REQUIRED > __IPHONE_6_0)
+
     template <class _Ch, class _Tr>
     friend
     _LIBCPP_HIDDEN
@@ -889,6 +897,7 @@ public:
     __pad_and_output(ostreambuf_iterator<_Ch, _Tr> __s,
                      const _Ch* __ob, const _Ch* __op, const _Ch* __oe,
                      ios_base& __iob, _Ch __fl);
+#endif
 };
 
 template <class _Iter>