Remove RD_CLIENT preprocessor.

Remove RD_CLIENT preprocessor.

RD_CLIENT preprocessor for relay notification are removed,
because resource directoty option has been set for default.
No need to set the option with WITH_CLOUD any more when building.

Change-Id: I3170b60f29c836dcf1ef18a1069a0bee09b4bd94
Signed-off-by: cc <ch79.cho@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/16425
Tested-by: jenkins-iotivity <jenkins@iotivity.org>
Reviewed-by: JungYong KIM <jyong2.kim@samsung.com>
Reviewed-by: Uze Choi <uzchoi@samsung.com>