```
This allows one to build the dependencies with the Android SDK and goes
towards fixing #11844. It has been tested to work with:
make HOST=aarch64-linux-android ANDROID_API_LEVEL=28
ANDROID_TOOLCHAIN_BIN=/home/user/Android/Sdk/ndk-bundle/toolchains/llvm/prebuilt/linux-x86_64/bin
NO_QT=1 NO_WALLET=1
```
Backport of core PR16110.
This allows for building the depends for android, and the software on
top. It's not very useful for now (no packaging) but it's a first step.
Note 1: The i686 build from the initial PR is broken with qt, fixed in
this diff.
Note 2: I made the README a bit more easier to follow, since we have
already taken ownership of the file.
Note 3: For now the cmake build is not successful. There are some Qt
issues (can find the main module but not its components ?).