Enable building androiddeployqt when performing host builds only.
Added QtPlatformAndroid.cmake to locate Java and the setup the
android SDK platform when building on android.
Install the androiddeployqt support files when performing a host
build.
Added ANDROID_SDK_ROOT configuration variable for specifying the
android sdk directory.
Generating the deployment-settings.json will be done in another
change.
Change-Id: I1bf15315af4ed904d2fb1d22b0e8e834df32d6ed
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
