Switch atmosphere's build target to C++20. (#952)

* ams: update to build with gcc10/c++20

* remove mno-outline-atomics

* ams: take care of most TODO C++20s

* fusee/sept: update for gcc10

* whoosh, your code now uses pre-compiled headers

* make: dependency fixes

stratosphere/ams_mitm/source/set_mitm/settings_sd_kvs.cpp

@@ -13,6 +13,7 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
+#include <stratosphere.hpp>
 #include "../amsmitm_debug.hpp"
 #include "../amsmitm_fs_utils.hpp"
 #include "settings_sd_kvs.hpp"
@@ -42,7 +43,7 @@ namespace ams::settings::fwdbg {
             }
         };
 
-        static_assert(std::is_pod<SdKeyValueStoreEntry>::value);
+        static_assert(util::is_pod<SdKeyValueStoreEntry>::value);
 
         constexpr inline bool operator==(const SdKeyValueStoreEntry &lhs, const SdKeyValueStoreEntry &rhs) {
             if (lhs.HasValue() != rhs.HasValue()) {