Travis sets up the GCOV variable to collect coverage and
provides an external mount for this. Thus handling this
option in RPC mode is essential.

travis-ci: success for tests: Add RPC testing to CI (rev2)
Acked-by: Andrey Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>