Fix bug for invalid access variable.

Fix bug for invalid access variable.

when access consumer main thread but  initialized, service will crash.
So this patch prevent invalid access to not initialized thread handle.

Change-Id: I77d86a712e0efe6bbec17780426df4a5ba98decc
Signed-off-by: KIM JungYong <jyong2.kim@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/12815
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Uze Choi <uzchoi@samsung.com>
(cherry picked from commit 7c6e61367021005ed0fdc401513629eb6fb48d07)
Reviewed-on: https://gerrit.iotivity.org/gerrit/12899