build: Exit with return code from builds

build: Exit with return code from builds

[Trevor Bramwell <tbramwell@linuxfoundation.org>]
The exit code from scons calls is being silently ignored. Returning the
exit code from 'wait()' in auto_build.py and passing it to 'exit()'
should correctly fail builds.

[Philippe Coval <philippe.coval@osg.samsung.com>]
To sort out and sync ourselves, I added Bug-Id to commit message.
Content is same, feel free keep that link and push over.

Change-Id: I5afce52a3bddf7fb4e6b68acb57a1d51f3034067
Signed-off-by: Trevor Bramwell <tbramwell@linuxfoundation.org>
Author: Trevor Bramwell <tbramwell@linuxfoundation.org>
Bug: https://jira.iotivity.org/browse/IOT-1260
Origin: https://gerrit.iotivity.org/gerrit/#/c/11087/
Signed-off-by: Philippe Coval <philippe.coval@osg.samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/11087
Reviewed-by: jihwan seo <jihwan.seo@samsung.com>
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: David Antler <david.a.antler@intel.com>
Reviewed-by: Uze Choi <uzchoi@samsung.com>