The following macros are now defined for openssl < 1.1 so that we
can remove the code performing direct access to the structures :
BIO_get_data(), BIO_set_data(), BIO_set_init(), BIO_meth_free(),
BIO_meth_new(), BIO_meth_set_gets(), BIO_meth_set_puts(),
BIO_meth_set_read(), BIO_meth_set_write(), BIO_meth_set_create(),
BIO_meth_set_ctrl(), BIO_meth_set_destroy()
It's always a pain to have to stuff lots of #ifdef USE_OPENSSL around
ssl headers, it even results in some of them appearing in a random order
and multiple times just to benefit form an existing ifdef block. Let's
make these headers safe for inclusion when USE_OPENSSL is not defined,
they now perform the test themselves and do nothing if USE_OPENSSL is
not defined. This allows to remove no less than 8 such ifdef blocks
and make include blocks more readable.
Since we're providing a compatibility layer for multiple OpenSSL
implementations and their derivatives, it is important that no C file
directly includes openssl headers but only passes via openssl-compat
instead. As a bonus this also gets rid of redundant complex rules for
inclusion of certain files (engines etc).
Some defines like OPENSSL_VERSION or X509_getm_notBefore() have nothing
to do in ssl_sock and must move to openssl-compat.h so that they are
consistently shared by the whole code. A warning in the code was added
against wild additions of macros there.
