The dejagnu tests for slabtop are skipped when "/proc/slabinfo" is
unreadable due to permissions. This commit provides the same check
for vmstat under its -m (slabinfo) option.
Makefile will now only test for Linux systems, a work around in the
makefile due to some silly redefine restrictions.
uptime and w now won't error due to being one user logged in, thanks to
Sami for the patch
kill processes by pid test commented out due to false negatives
pwdx process 1 check also commented out due to false negatives