Revert "Use BIO* in _privatekey_from_file [Oliver Stöneberg]"
Revert "Use BIO* in _privatekey_from_file [Oliver Stöneberg]"

This reverts commit da8356b477fc94a18b8098f021a25d7e24ee79de.

mwgoldsmith/libssh,mwgoldsmith/ssh,mwgoldsmith/ssh,mwgoldsmith/libssh,mwgoldsmith/ssh,mwgoldsmith/libssh,mwgoldsmith/libssh,mwgoldsmith/ssh