Of the two ways to run the NSPR tests: runtests.ksh and runtests.sh, the later appears to be the correct one. The runtests.ksh should be CVS removed to prevent confusion. make runtests should also be implemented to allow the build system to automatically run the tests. The script runtests.sh should still work stand alone to allow testing outside the build environment.
This file was removed as part of Bug 307573: https://hg.mozilla.org/projects/nspr/rev/57f0afd165d6