libstdc++: Fix a few !HOSTED test regressions

libstdc++-v3/ChangeLog:

	* testsuite/20_util/to_chars/version.cc: Mark hosted-only.
	* testsuite/20_util/uses_allocator/lwg3677.cc: Ditto.
	* testsuite/20_util/weak_ptr/cons/self_move.cc: Ditto.
	* testsuite/std/ranges/adaptors/as_rvalue/1.cc: Replace usage of
	std::make_unique with a freestanding-compatible wrapper around
	unique_ptr.
	* testsuite/21_strings/basic_string_view/operations/contains/char.cc:
	Don't test for presence of __cpp_lib_string_contains on !HOSTED.
	* testsuite/21_strings/basic_string_view/operations/contains/char/2.cc:
	Ditto.
	* testsuite/std/ranges/version_c++23.cc: Don't test for presence
	of __cpp_lib_ranges in !HOSTED.

libstdc++-v3/testsuite/20_util/to_chars/version.cc

@@ -1,5 +1,6 @@
 // { dg-options "-std=gnu++23" }
 // { dg-do preprocess { target c++23 } }
+// { dg-require-effective-target hosted }
 
 #include <version>
 

libstdc++-v3/testsuite/20_util/uses_allocator/lwg3677.cc

@@ -1,5 +1,6 @@
 // { dg-options "-std=gnu++23" }
 // { dg-do run { target c++20 } }
+// { dg-require-effective-target hosted }
 
 #include <memory>
 #include <testsuite_hooks.h>

libstdc++-v3/testsuite/20_util/weak_ptr/cons/self_move.cc

@@ -1,4 +1,5 @@
 // { dg-do run { target c++11 } }
+// { dg-require-effective-target hosted }
 
 #include <memory>
 #include <testsuite_hooks.h>

libstdc++-v3/testsuite/21_strings/basic_string_view/operations/contains/char.cc

@@ -22,11 +22,14 @@
 
 #include <string_view>
 
-#ifndef __cpp_lib_string_contains
-# error "Feature-test macro for contains missing in <string_view>"
-#elif __cpp_lib_string_contains != 202011L
-# error "Feature-test macro for contains has wrong value in <string_view>"
-#endif
+#if __STDC_HOSTED__
+// This FTM is omitted since <string> is not freestanding.
+# ifndef __cpp_lib_string_contains
+#  error "Feature-test macro for contains missing in <string_view>"
+# elif __cpp_lib_string_contains != 202011L
+#  error "Feature-test macro for contains has wrong value in <string_view>"
+# endif
+#endif // HOSTED
 
 void
 test01()

libstdc++-v3/testsuite/21_strings/basic_string_view/operations/contains/char/2.cc

@@ -20,8 +20,11 @@
 
 #include <version>
 
-#ifndef __cpp_lib_string_contains
-# error "Feature-test macro for contains missing in <string_view>"
-#elif __cpp_lib_string_contains != 202011L
-# error "Feature-test macro for contains has wrong value in <string_view>"
+#if __STDC_HOSTED__
+// This FTM is omitted since <string> is not freestanding.
+# ifndef __cpp_lib_string_contains
+#  error "Feature-test macro for contains missing in <string_view>"
+# elif __cpp_lib_string_contains != 202011L
+#  error "Feature-test macro for contains has wrong value in <string_view>"
+# endif
 #endif

libstdc++-v3/testsuite/std/ranges/adaptors/as_rvalue/1.cc

@@ -14,13 +14,24 @@
 namespace ranges = std::ranges;
 namespace views = std::views;
 
+
+/* Replacement for the standard version, as it's not available in freestanding
+   environments.  */
+template<typename T, typename... Args>
+requires (!std::is_array_v<T>)
+constexpr auto
+make_unique (Args &&...args)
+{
+  return std::unique_ptr<T> { new T (std::forward<Args>(args)...) };
+}
+
 constexpr bool
 test01()
 {
 
-  std::unique_ptr<int> a[3] = { std::make_unique<int>(1),
-				std::make_unique<int>(2),
-				std::make_unique<int>(3) };
+  std::unique_ptr<int> a[3] = { make_unique<int>(1),
+				make_unique<int>(2),
+				make_unique<int>(3) };
   std::unique_ptr<int> b[3];
   auto v = a | views::as_rvalue;
   ranges::copy(v, b);
@@ -33,7 +44,7 @@ test01()
 void
 test02()
 {
-  std::unique_ptr<int> x = std::make_unique<int>(42);
+  std::unique_ptr<int> x = make_unique<int>(42);
   std::unique_ptr<int> y;
   __gnu_test::test_input_range rx(&x, &x+1);
   auto v = rx | views::as_rvalue;

libstdc++-v3/testsuite/std/ranges/version_c++23.cc

@@ -3,8 +3,10 @@
 
 #include <version>
 
-#if __cpp_lib_ranges != 202110L
-# error "Feature-test macro __cpp_lib_ranges has wrong value in <version>"
+#if __STDC_HOSTED__
+# if __cpp_lib_ranges != 202110L
+#  error "Feature-test macro __cpp_lib_ranges has wrong value in <version>"
+# endif
 #endif
 
 #if __cpp_lib_ranges_zip != 202110L