binder: Fix setRpcClientDebug in binderLibTest.

Similar to binderRpcTest, the test may run on VTS
on a user build. In this case setRpcClientDebug
is not available. Check return code accordingly.

Test: TH
Fixes: 221186690
Change-Id: Ib86c6f98af5652d8db0185b1889c154842a33adb
Merged-In: Ib86c6f98af5652d8db0185b1889c154842a33adb