correct incorrect years in datestamps; from des
 - (djm) [openbsd-compat/arc4random.c openbsd-compat/chacha_private.h] Pull
   in OpenBSD implementation of arc4random, shortly to replace the existing
   bsd-arc4random.c
 - (djm) [openbsd-compat/Makefile.in openbsd-compat/arc4random.c]
   [openbsd-compat/bsd-arc4random.c] Replace old RC4-based arc4random
   implementation with recent OpenBSD's ChaCha-based PRNG. ok dtucker@,
   tested tim@