vdlog.cpp has an #ifdef check for OLDMSVC to choose between using
swprintf or swprintf_s. Since vdcommon.h provides a compat #define
for swprintf_s when OLDMSVC is set, it's better to use this one.
Apparently, it comes with a recent version of C library (msvcrt90?),
but I don't know if we can/should ship also a MS dll. Probably it used
to work with an inlined version with VS headers.
The build can be tweaked to use the -non-_s variant with -DOLDMSVCRT
CFLAGS.
