Fix build issue of unittest.
Fix build issue of unittest.

When notification service unittest build with '-Wl, --as-needed' LDFLAGS,
some build machine building fail.(this flag is default option.)
The default of passing --as-needed can be undone by passing --no-as-needed to the linker.
So, 'Wl, --no-as-needed' flag is added in notification unittest SConscript.

Change-Id: Ifb56d0af433b58fc3bcbbd8938c9c318a21035c4
Signed-off-by: KIM JungYong <a7fda6cb43a99323e7403e06467da5520755bdcc@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/10127
Tested-by: jenkins-iotivity <09cb29e8a2b473a2c978382eec13ee06fa017bda@opendaylight.org>
Reviewed-by: Madan Lanka <f0ab8ffa6f9be130982d9ec09d220706b52daee1@samsung.com>

iotivity/iotivity,rzr/iotivity,rzr/iotivity,iotivity/iotivity,rzr/iotivity,iotivity/iotivity,rzr/iotivity,iotivity/iotivity,iotivity/iotivity,iotivity/iotivity,rzr/iotivity,rzr/iotivity,iotivity/iotivity,iotivity/iotivity,rzr/iotivity