"test_control_logging_tests.c" don't use CMock

I have in mind to test the 'va_list' ability of 'writeLog()' in order
to put unexpected messages from the master in the log file. I want
to avoid obscuring the log file with unannounced data so the
unexpected message needs to be prefixed with a statement of what it
is. In order to do that I need to combine strings, and for that
'writeLog()'s ability to use 'printf'-formatting "%s" is very handy.
The problem: CMock doesn't mock 'va_list'. Therefore: Use a
hand-written mock of 'writeLog()'.