rpc01: moved the library into a separate directory

Cyril Hrubis noticed that including both
  * lib.mk and
  * generic_trunk_target.mk
in one Makefile results in a situation when MAKE_TARGETS are installed twice,
into /testcases/bin and /lib.

Therefore we are moving the library into a separate directory.

Signed-off-by: Stanislav Kholmanskikh <stanislav.kholmanskikh@oracle.com>