If some other thread deletes the BIO that one thread needs for
BIO_write, then there's a lot of trouble anyway; there's
nothing special about calling the callback.
like Malloc, Realloc and especially Free conflict with already existing names
on some operating systems or other packages. That is reason enough to change
the names of the OpenSSL memory allocation macros to something that has a
better chance of being unique, like prepending them with OPENSSL_.
This change includes all the name changes needed throughout all C files.
designed for that. This removes the potential error to mix data and
function pointers.
Please note that I'm a little unsure how incorrect calls to the old
ctrl functions should be handled, in som cases. I currently return 0
and that's it, but it may be more correct to generate a genuine error
in those cases.