build: Format SConscript as consistant python source

build: Format SConscript as consistant python source

Use 4 spaces for tabulation

Bug: https://gerrit.iotivity.org/gerrit/#/c/9783/4
Change-Id: I5b27d4c573e43d1c7b069ec417133340f8c36a44
Origin: https://gerrit.iotivity.org/gerrit/#/c/11265/
Signed-off-by: Philippe Coval <philippe.coval@osg.samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/11265
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: David Antler <david.a.antler@intel.com>
Reviewed-by: Dave Thaler <dthaler@microsoft.com>