Fix propagation of libtirpc flags into build of test source.

Fix propagation of libtirpc flags into build of test source.

Starting with glibc 2.32, the Linux libc<n>-dev no longer provides
the /usr/include/rpc/rpc.h header.  The configure script will detect
the availability of the libtirpc package and use the rpc.h header
from /usr/include/tirpc/rpc/rpc.h.

This fix extends the necessary compilation and linking options to the
build of the open-vm-tools services test programs that utilize RPC.

Fixes: https://github.com/vmware/open-vm-tools/issues/468
Pull Request: https://github.com/vmware/open-vm-tools/pull/469