fs_mitm: Fix mismatched new[] / delete (#389)

* fs.mitm: Fix mismatched new[] / delete

Using delete instead of delete[] on a pointer given by new[] is
undefined behaviour.

For memory sources, malloc/free are used because cleaning up is tricky
when data can be either allocated with new (RomfsHeader) or new[]
(metadata).

* set.mitm: Fix mismatched new[] / delete

stratosphere/ams_mitm/source/set_mitm/setsys_settings_items.cpp

@@ -257,7 +257,7 @@ void SettingsItemManager::LoadConfiguration() {
     char *config_buf = new char[0x10000];
     std::memset(config_buf, 0, 0x10000);
     ON_SCOPE_EXIT {
-        delete config_buf;
+        delete[] config_buf;
     };
     
     /* Read from file. */