test/rpc: fix test execution

* fix compilation from the test/rpc directory

$ make
make: *** No rule to make target `/rpc.proto', needed by `rpc.pb-c.c'. Stop.

* use absolute path for pidfile

$ bash run.sh
**************************************************
		Shutdown service server
**************************************************

cat: pidfile: No such file or directory
kill: usage: kill [-s sigspec | -n signum | -sigspec] pid | jobspec ...
or kill -l [sigspec]

Cc: Ruslan Kuprieiev <kupruser@gmail.com>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>