libstdc++: Shuffle header dependencies of <functional>

The <new> header is needed by std::function to use placement new, so
include it in <bits/std_function.h> instead of in <functional>.

libstdc++-v3/ChangeLog:

	* include/bits/std_function.h: Include <new> but do not include
	<bits/stl_function.h>.
	* include/std/functional: Do not include <new>.

libstdc++-v3/include/bits/std_function.h

@@ -36,11 +36,11 @@
 # include <bits/c++0x_warning.h>
 #else
 
-#include <typeinfo>
-#include <bits/stl_function.h>
-#include <bits/invoke.h>
-#include <bits/refwrap.h>
-#include <bits/functexcept.h>
+#include <new>                // placement new
+#include <typeinfo>           // typeid
+#include <bits/invoke.h>      // __invoke_r
+#include <bits/refwrap.h>     // ref wrapper, _Maybe_unary_or_binary_function
+#include <bits/functexcept.h> // __throw_bad_function_call
 
 namespace std _GLIBCXX_VISIBILITY(default)
 {

libstdc++-v3/include/std/functional

@@ -46,11 +46,10 @@
 #pragma GCC system_header
 
 #include <bits/c++config.h>
-#include <bits/stl_function.h>
+#include <bits/stl_function.h> // std::equal_to, std::unary_function etc.
 
 #if __cplusplus >= 201103L
 
-#include <new>
 #include <tuple>
 #include <type_traits>
 #include <bits/functional_hash.h>
@@ -67,8 +66,8 @@
 # endif
 # include <bits/stl_algo.h> // std::search
 #endif
-#if __cplusplus > 201703L
-# include <bits/ranges_cmp.h>
+#if __cplusplus >= 202002L
+# include <bits/ranges_cmp.h> // std::identity, ranges::equal_to etc.
 # include <compare>
 #endif
 #if __cplusplus > 202002L && _GLIBCXX_HOSTED