To run usb test, go to sim directory(../../cosim/usb_arc/sim)
./vcs_verilog_runtest.linux

To rebuild pli library(under chip/cosim/usb_arc)
cd software/bfm/co_simulation/tests/vusb/lib-linux
make 
cd software/vcs/linux
make vcs

Note:
To compile pli library, you need to use gcc 2.96(not come with redhat 6.2) 
or above and download systemC 1.1 or above. And you also need to change
SYSTEMC in makedefs before you run make.