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

libraries/libstratosphere/source/fs/fs_file_path_hash.hpp

@@ -23,7 +23,7 @@ namespace ams::fs::impl {
     struct FilePathHash : public Newable {
         u8 data[FilePathHashSize];
     };
-    static_assert(std::is_pod<FilePathHash>::value);
+    static_assert(util::is_pod<FilePathHash>::value);
 
     inline bool operator==(const FilePathHash &lhs, const FilePathHash &rhs) {
         return std::memcmp(lhs.data, rhs.data, FilePathHashSize) == 0;

libraries/libstratosphere/source/fs/fsa/fs_mount_name.hpp

@@ -21,6 +21,6 @@ namespace ams::fs {
     struct MountName {
         char str[MountNameLengthMax + 1];
     };
-    static_assert(std::is_pod<MountName>::value);
+    static_assert(util::is_pod<MountName>::value);
 
 }