Android: fixing scons build for the examples

Android: fixing scons build for the examples

The issue in scons script introduced in
https://gerrit.iotivity.org/gerrit/#/c/3135/ and consequently
in https://gerrit.iotivity.org/gerrit/#/c/3287/ has caused
the long build times for the Android examples by rebuilding
it multiple times.

Change-Id: I978ac3459dbd0e42e231f8d70a0374558e85f9e8
Signed-off-by: Tim Kourt <tim.a.kourt@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/3329
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Uze Choi <uzchoi@samsung.com>