util: warn if UTI_OpenFile() is stuck in a loop

util: warn if UTI_OpenFile() is stuck in a loop

When UTI_OpenFile() is removing an existing file to be replaced by a new
file, it could potentially get stuck in an infinite loop if something
was able to consistently win the race and create a new file before
chronyd.

Log a warning message after 100 failed attempts and repeat on each 10x
increase to make it more obvious to the admin, if it ever happens.

Reported-by: Eric Sesterhenn <eric.sesterhenn@x41-dsec.de>