[libc++][PSTL] Implement std::replace{,_if,_copy,_copy_if}

Reviewed By: #libc, ldionne

Spies: ldionne, libcxx-commits

Differential Revision: https://reviews.llvm.org/D151841
diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
index 04a21c0..2ceedc9 100644
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -1807,6 +1807,7 @@
 #include <__algorithm/pstl_find.h>
 #include <__algorithm/pstl_for_each.h>
 #include <__algorithm/pstl_merge.h>
+#include <__algorithm/pstl_replace.h>
 #include <__algorithm/pstl_stable_sort.h>
 #include <__algorithm/pstl_transform.h>
 #include <__algorithm/push_heap.h>