test failures on armhf build

Hi,

as part of the librtpi packaging for debian, I noticed that some tests sporadically fail on armhf (build for debian sid, linux 6.7.12).

FAIL: tst-cond6
===============

going to fork now
parent: cond_wait failed
child done
FAIL tst-cond6 (exit status: 1)

FAIL: tst-cond11
================

clock = 0
timeout too short
clock = 1
timeout too short
FAIL tst-cond11 (exit status: 1)