Remove reference to obj/lib

It's going away, since we don't have a single library on device anymore,
and it's simpler to keep the host looking like the device. This doesn't
seem to need it anymore either -- the libraries are found relative to
the test binary.

Test: bionic/tests/run-on-host.sh glibc
Change-Id: Ie9bf6388ecd773623181ec9eadb35d6e0ba0a441