A Native Android build (Boot to Qt Android injection) is defined by
having both Q_OS_ANDROID and Q_OS_ANDROID_EMBEDDED flags defined,
as well as having Qt config android-embedded.
Those flags are set in mkspecs when building for embedded Android.
This commit enables the possibility to build native Android builds
(i.e. Qt build for Android baselayer only, without JNI)

Change-Id: I3f88568f34502c6cfafadbbebd4dd2212a3cd0c4
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>