[pstl][libc++] Provide uglified header names for interface headers

For the few (currently four) headers that make up the PSTL's interface
to other Standard Libraries, provide a stable uglified header file that
can be included by those Standard Libraries.

We can then more easily change the internal organization of the PSTL
without having to change the integration with Standard Libraries.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@368088 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/algorithm b/include/algorithm
index ac780af..91cca5c 100644
--- a/include/algorithm
+++ b/include/algorithm
@@ -5679,7 +5679,7 @@
 _LIBCPP_POP_MACROS
 
 #if defined(_LIBCPP_HAS_PARALLEL_ALGORITHMS) && _LIBCPP_STD_VER >= 17
-#   include <pstl/internal/glue_algorithm_impl.h>
+#   include <__pstl_algorithm>
 #endif
 
 #endif  // _LIBCPP_ALGORITHM
diff --git a/include/execution b/include/execution
index c12615b..e25cb82 100644
--- a/include/execution
+++ b/include/execution
@@ -13,7 +13,7 @@
 #include <__config>
 
 #if defined(_LIBCPP_HAS_PARALLEL_ALGORITHMS) && _LIBCPP_STD_VER >= 17
-#   include <pstl/internal/glue_execution_defs.h>
+#   include <__pstl_execution>
 #endif
 
 #endif // _LIBCPP_EXECUTION
diff --git a/include/memory b/include/memory
index ff500f8..321d5fe 100644
--- a/include/memory
+++ b/include/memory
@@ -5591,7 +5591,7 @@
 _LIBCPP_POP_MACROS
 
 #if defined(_LIBCPP_HAS_PARALLEL_ALGORITHMS) && _LIBCPP_STD_VER >= 17
-#   include <pstl/internal/glue_memory_impl.h>
+#   include <__pstl_memory>
 #endif
 
 #endif  // _LIBCPP_MEMORY
diff --git a/include/numeric b/include/numeric
index f5ac141..854bbfa 100644
--- a/include/numeric
+++ b/include/numeric
@@ -587,7 +587,7 @@
 _LIBCPP_POP_MACROS
 
 #if defined(_LIBCPP_HAS_PARALLEL_ALGORITHMS) && _LIBCPP_STD_VER >= 17
-#   include <pstl/internal/glue_numeric_impl.h>
+#   include <__pstl_numeric>
 #endif
 
 #endif  // _LIBCPP_NUMERIC