Specify proper default SCons parameter build values for Android.

Specify proper default SCons parameter build values for Android.

This will allow an end user to simply issue "scons TARGET_OS=android" and
expect the build to work. Before this, end users had to specify
the TARGET_TRANSPORT & TARGET_ARCH parameters every time.

Change-Id: I48cea638a441fa55b1a82d320cd2a65b6cc39c01
Signed-off-by: Joseph Morrow <joseph.l.morrow@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/1154
Reviewed-by: Erich Keane <erich.keane@intel.com>
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>