Use BUF_strlcat() instead of strcat().
Use BIO_snprintf() instead of sprintf().
In some cases, keep better track of buffer lengths.
This is part of a large change submitted by Markus Friedl <markus@openbsd.org>
change the way ASN1 modules are exported.
Still needs a bit of work for example the hack which a
dummy function prototype to avoid compilers warning about
multiple ;s.