We already have our own signal safe vnsprintf() implementation, which is used
for formatting log messages while being in a signal handler, there's no need
to have two separate implementations of all the logging functions.
Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1691>