Almost nothing actually needs to include <openssl/e_os2.h>, however by
including it they get <openssl/opensslconf.h>. So instead of pulling in
<openssl/e_os2.h>, just pull in <openssl/opensslconf.h>.

"go ahead" miod@
Explicitly include <openssl/openssl.conf>. des.h still needs e_os2.h (at
least for a little while longer...)
e_os2.h is not needed here.
Another e_os2.h -> opensslconf.h.