[libc++][NFC] Move __insertion_sort_move to partial_sort.h

[ldionne]

Summary

The __insertion_sort_move helper function is only used in partial_sort.h,
so it makes sense to define it there.

libcxx/include/__algorithm/sort.h

 #include <__bit/countl.h>
 #include <__bit/countr.h>
 #include <__config>
 #include <__debug>
 #include <__debug_utils/randomize_range.h>
 #include <__functional/operations.h>
 #include <__functional/ranges_operations.h>
 #include <__iterator/iterator_traits.h>
-#include <__memory/destruct_n.h>
-#include <__memory/unique_ptr.h>
 #include <__type_traits/conditional.h>
 #include <__type_traits/disjunction.h>
 #include <__type_traits/is_arithmetic.h>
 #include <__utility/move.h>
 #include <__utility/pair.h>
 #include <climits>
 #include <cstdint>
 
if (__comp(*__i, *__j)) {
       if (++__count == __limit)
         return ++__i == __last;
     }
     __j = __i;
   }
   return true;
 }
 
-template <class _AlgPolicy, class _Compare, class _BidirectionalIterator>
-_LIBCPP_HIDE_FROM_ABI
-void __insertion_sort_move(_BidirectionalIterator __first1, _BidirectionalIterator __last1,
-                           typename iterator_traits<_BidirectionalIterator>::value_type* __first2, _Compare __comp) {
-  using _Ops = _IterOps<_AlgPolicy>;
-
-  typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
-  if (__first1 != __last1) {
-    __destruct_n __d(0);
-    unique_ptr<value_type, __destruct_n&> __h(__first2, __d);
-    value_type* __last2 = __first2;
-    ::new ((void*)__last2) value_type(_Ops::__iter_move(__first1));
-    __d.template __incr<value_type>();
-    for (++__last2; ++__first1 != __last1; ++__last2) {
-      value_type* __j2 = __last2;
-      value_type* __i2 = __j2;
-      if (__comp(*__first1, *--__i2)) {
-        ::new ((void*)__j2) value_type(std::move(*__i2));
-        __d.template __incr<value_type>();
-        for (--__j2; __i2 != __first2 && __comp(*__first1, *--__i2); --__j2)
-          *__j2 = std::move(*__i2);
-        *__j2 = _Ops::__iter_move(__first1);
-      } else {
-        ::new ((void*)__j2) value_type(_Ops::__iter_move(__first1));
-        __d.template __incr<value_type>();
-      }
-    }
-    __h.release();
-  }
-}
-
 template <class _AlgPolicy, class _RandomAccessIterator>
 inline _LIBCPP_HIDE_FROM_ABI void __swap_bitmap_pos(
     _RandomAccessIterator __first, _RandomAccessIterator __last, uint64_t& __left_bitset, uint64_t& __right_bitset) {
   using _Ops = _IterOps<_AlgPolicy>;
   typedef typename std::iterator_traits<_RandomAccessIterator>::difference_type difference_type;
   // Swap one pair on each iteration as long as both bitsets have at least one
   // element for swapping.
   while (__left_bitset != 0 && __right_bitset != 0) {

libcxx/include/__algorithm/stable_sort.h

 #include <new>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
 #endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
+template <class _AlgPolicy, class _Compare, class _BidirectionalIterator>
+_LIBCPP_HIDE_FROM_ABI
+void __insertion_sort_move(_BidirectionalIterator __first1, _BidirectionalIterator __last1,
+                           typename iterator_traits<_BidirectionalIterator>::value_type* __first2, _Compare __comp) {
+  using _Ops = _IterOps<_AlgPolicy>;
+
+  typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
+  if (__first1 != __last1) {
+    __destruct_n __d(0);
+    unique_ptr<value_type, __destruct_n&> __h(__first2, __d);
+    value_type* __last2 = __first2;
+    ::new ((void*)__last2) value_type(_Ops::__iter_move(__first1));
+    __d.template __incr<value_type>();
+    for (++__last2; ++__first1 != __last1; ++__last2) {
+      value_type* __j2 = __last2;
+      value_type* __i2 = __j2;
+      if (__comp(*__first1, *--__i2)) {
+        ::new ((void*)__j2) value_type(std::move(*__i2));
+        __d.template __incr<value_type>();
+        for (--__j2; __i2 != __first2 && __comp(*__first1, *--__i2); --__j2)
+          *__j2 = std::move(*__i2);
+        *__j2 = _Ops::__iter_move(__first1);
+      } else {
+        ::new ((void*)__j2) value_type(_Ops::__iter_move(__first1));
+        __d.template __incr<value_type>();
+      }
+    }
+    __h.release();
+  }
+}
+
 template <class _AlgPolicy, class _Compare, class _InputIterator1, class _InputIterator2>
 _LIBCPP_HIDE_FROM_ABI void
 __merge_move_construct(_InputIterator1 __first1, _InputIterator1 __last1,
         _InputIterator2 __first2, _InputIterator2 __last2,
         typename iterator_traits<_InputIterator1>::value_type* __result, _Compare __comp)
 {
     using _Ops = _IterOps<_AlgPolicy>;