Prepare to remove the _cb() and _fp() versions of BIO_dump()

Prepare to remove the _cb() and _fp() versions of BIO_dump()

apache-httpd uses BIO_dump(), libssl uses BIO_dump_indent(), and the
openssl(1) app uses both. Otherwise this is unused. This is horribly
bad code even by libcrypto standards.

By doing away with the callbacks fixes incorrect error checking for
fwrite() but there is a lot more wrong in here. This can be cleaned
up in a later pass, the only concern here is to be able to remove the
unused variants in the next major bump.

ok beck