Xenomai runtime: report and mitigate when PLC cycle overruns.

Side effect :
_Log* macro was changed in plc_Xenomai_main.c,
and fixed in plc_Linux_main.c

<?xml version='1.0' encoding='utf-8'?>
<BaseParams xmlns:xsd="http://www.w3.org/2001/XMLSchema" IEC_Channel="1" Name="py_ext_0"/>