Pass ANDROID_ABI & ANDROID_NDK variables to cmake

[CAMOBAP]

Intro

Recently In bincrafters/conan-libwebp#5 I faced with issues conan don't forward ANDROID_ABI variable and didn't have any way to pass ANDROID_NDK to cmake script too

Most of libraries with cmake build system which support Android expect these variables

Proposal

Pass ANDROID_ABI which can be determined from os.settings.arch
Pass ANDROID_NDK if ANDROID_NDK_HOME environment variable defined (name of env variable can be discussed)

[CAMOBAP]

Looks like make sense to care about ANDROID_NDK_ROOT too

[venabled]

Also helpful even if you pass the Platform/Level somewhere as well, detectable from op_system_version

            ret["ANDROID_PLATFORM"] = op_system_version

[CAMOBAP]

@venabled ANDROID_PLATFORM isn't just api level it's in format android-$api_level

BTW PR already contains this

[venabled]

Copy, didn't follow the conversation into the PR. Will try out that branch here shortly.