Update pthread_cond_timedwait() test to current NetBSD version

[vangyzen]

Summary

NetBSD adapted and committed our r350620. Update to their version 1.8.

Test Plan

I ran it on both bhyve and bare metal.

# kyua test -k /usr/tests/lib/libthr/Kyuafile condwait_test
condwait_test:cond_wait_mono  ->  passed  [2.127s]
condwait_test:cond_wait_real  ->  passed  [2.055s]

Results file id is usr_tests_lib_libthr.20190815-204903-586771
Results saved to /root/.kyua/store/results.usr_tests_lib_libthr.20190815-204903-586771.db

2/2 passed (0 failed)

[ngie]