[Android] Updating minsdk to 21

[rh101]

The minsdk is currently set to 17, which is for Android 4. Is this OS still being actively used? If not, would anyone have any issues if we bump up the version to minsdk to 21?

The reason has to do with having AxmolActivity inherit from AppCompatActivity rather than Activity, which has been brought up before in #1891. It allows for a lot of functionality that is missing in Activity, but unfortunately it requires minsdk to be 21.

@halx99 Do you have any opinion regarding this?

[halx99]

Maybe upgrade minsdk=21 and ndk=27+ in axmol-3.x plan better

[rh101]

If that's the case, then I'll see if I can just work around the issues I have at the moment, or just use the branch on my own fork with the changes to AppCompatActivity and minsdk 21, until Axmol 3 is released.

By the way, if you want to see all changes, they're in this branch.

[halx99]

I upgrade branch 3.x ndk to r27c and cherry-pick your AppCompatActivity changes into it

[rh101]

Excellent!

Just FYI, I did manage to find a work-around for the issue I was having on Android with Axmol v2.3.0, so I'm still able to use the dev branch without any changes.