Always initialize fullscreen in display_win32_alert
Fix format mismatch on Win32 newdemo

Win32 makes sizeof(object) an unsigned int instead of unsigned long.
Fix const mismatch in digi_win32_play_midi_song
Fix format mismatch on Win32 draw_window_label

Win32 makes (pointer1-pointer2) an int instead of long.
Fix format mismatch on Win32 HandleTestKey

Win32 needs a special modifier to represent an int64_t parameter.
Fix format mismatch on Win32 centers_dialog_handler

Win32 makes (pointer1-pointer2) an int instead of long.
Fix format mismatch on Win32 info_display_default

Win32 makes (pointer1-pointer2) an int instead of long.