Compilation on Android with Qt 5.15

Now builds apk on Android with Qt 5.12 or Qt 5.15.

Output is now in ${build_folder}/android-build (instead of ${build_folder}/android previously).

Drawback: apk with Qt 5.15 is around 9Mo bigger. I think it's due to the non compression of Qt qml files which were before copied in plain text in the apk and are now in a rcc...

@timotheegiet: scripts have been updated to pass as first argument the Qt path (something like ~/Qt/5.x.y) to be able to handle both Qt 5.12 and Qt 5.15. Is it ok with you if I merge all the scripts to first pass the architecture and then the Qt version? The 3 scripts are basically doing the same...