Default sampgdk_logprintf_impl to printf()
Default sampgdk_logprintf_impl to printf()

This makes it possible to use sampgdk_[v]logprintf() before the
library gets initialized, e.g. to report failures in module init
routines.

Zeex/sampgdk,Zeex/sampgdk,WopsS/sampgdk,WopsS/sampgdk,WopsS/sampgdk,Zeex/sampgdk