Fix Android toolchain

[CaptainJet]

The NDK no longer supports mips, plain armeabi, or gcc. Remove old build_config for armeabi.
Update minimum sdk.
Fix tooling paths and targets.

[matz]

Thank you!

[gsantner]

Hello @CaptainJet,

I tried to compile mruby using this new configuration. Unfortunately it errors with some missing library/include error regarding readline.h (indeed Android NDK doesn't contain a readline.h).

Was this also the case back then and is there any special prerequisites required for mruby on Android?

Call:

env MRUBY_CONFIG="android_arm64_v8a" ANDROID_NDK_HOME="<somepath>/android/sdk_linux64/ndk/23.1.7779620" rake

Beside that 23.1 NDK version I also tried 25.1.8937393, but no difference.

[CaptainJet]

I generally recommend not compiling the executables like mirb when making the Android builds. I'm afraid I can't really help you debug it myself. Good luck though!

[gsantner]

@CaptainJet Thank you for the very fast response!

I'm actually more interested in getting ruby included so I can run some ruby code via C++/NDK on Android. Don't really need interactive in this case I guess 😄

OK, so when I disable all additional ... command at default.gembox then it compiles successfully.

So isn't it wrong to specify default.gembox at the android configuration, as it is not compatible? I couldn't find any DISABLE_TOOLS=true environment flag either to disable this stuff so it could be built without manually touching the git state of mruby.

@matz
Sorry I'm really new to the project and it seemingly has some default configuration issues. Would it be an option to have a default-notools.gembox configuration for example, or wrap the tools in the default.gembox with a if ENV['something'] ..? What do you think, does that make sense? In other projects often also flags like of WITH_TOOLS=true/false can be found to control compilation of potential unnecessary utilities.
I can make a first contribution by making a merge request containing a working default configuration for Android, if I get to know if it wanted and roughly how it's wanted