Default launch mode (standard) allows multiple instances of the SDLActivity.
( https://developer.android.com/guide/topics/manifest/activity-element#lmode )
Not sure this is intended in SDL as this doesn't work. There are static
variables in Java, in C code which make this impossible (allow one android_window) and
also Audio print errors.
There is also some code added in onDestroy as if it would be able to
re-initialize: https://hg.libsdl.org/SDL/rev/56e9c709db7e
Bug Android activity life-cycle seems to show there is not transition to get out
of onDestroy()
https://developer.android.com/reference/android/app/Activity#ActivityLifecycle
( can be tested with "adb shell am start my.package.org/.MainActivity"
and "adb shell am start -n my.package.org/.MainActivity" )
Send me a message if there are real use-case for this !
