Android Platform: find a way to build Xemu for Android ;)

[lgblgblgb]

In theory, SDL2 apps can be built for Android not so hard. Investigate if it's possible and how. This is maybe a minor issue (and probably wouldn't be fast enough for Mega65 emulation - though other emulators inside Xemu including C65 is more realistic to have OK speed - at least), but would be fun, anyway ;)