Some tests fail under musl/busybox

If you build procps and patch the configure so that it considers linux+musl as "linux", a handful of tests fail:

free.log:FAIL: free with negative repeat count
free.log:FAIL: free with zero repeat count
lib.log:FAIL: test no space left on device
pkill.log:FAIL: pkill with trailing garbage on int signal
ps.log:FAIL: ps SCHED_BATCH scheduler

Stepping through them:

spawn /home/rosbur01/Code/drive-by/procps/src/free -c -2
free: failed to parse count argument: '-2': Result not representable
FAIL: free with negative repeat count
spawn /home/rosbur01/Code/drive-by/procps/src/free -c 0
free: failed to parse count argument: '0': Result not representable
FAIL: free with zero repeat count

The expected error message is "Numerical result out of range", different errno strings in musl?

spawn ./lib.test/fileutils_full.sh
test_fileutils: write error
FAIL: test no space left on device

Not sure what causes this.

spawn /home/rosbur01/Code/drive-by/procps/src/pkill -0garbage spcorp
/home/rosbur01/Code/drive-by/procps/src/.libs/pkill: unrecognized option: 0

Usage:
 pkill [options] <pattern>
[...]

FAIL: pkill with trailing garbage on int signal

This appears to be busybox pkill vs GNU pkill.

testcase /home/rosbur01/Code/drive-by/procps/testsuite/ps.test/ps_personality.exp completed in 0 seconds
Running /home/rosbur01/Code/drive-by/procps/testsuite/ps.test/ps_sched_batch.exp ...
spawn /home/rosbur01/Code/drive-by/procps/testsuite/test-schedbatch 18
spawn /home/rosbur01/Code/drive-by/procps/src/ps/pscommand --no-header -o comm,cls,nice -ax
systemd          TS   0
kthreadd         TS   0
pool_workqueue_  TS   0
kworker/R-rcu_g  TS -20
kworker/R-rcu_p  TS -20
[...]
kworker/u300:1-  TS   0
kworker/u278:2-  TS   0
kworker/u318:1-  TS   0
bash             TS   0
kworker/u261:1-  TS   0
kworker/u274:0-  TS   0
kworker/u304:1-  TS   0
FAIL: ps SCHED_BATCH scheduler

Not sure.