Fix OldSystemTest#test_load

Previous change of findFlibrary argument from "c" to
"art" was unfortunate, as it wasn't accessible the
classloader namespace. Changed to "c++" that is present
in host library paths (so test_load on host can pass),
and should work fine on device.

Test: OldSystemTest run on vogar on host&device and through cts
Bug: 31174979
Change-Id: I6507c4068f04098b38194cbf6df31e59d71813ee
1 file changed