Add missing #ifndefs that caused missing symbols when building libssl

as a shared library without RSA.  Use #ifndef NO_SSL2 instead of
NO_RSA in ssl/s2*.c.

Submitted by: Kris Kennaway <kris@hub.freebsd.org>
Modified by Ulf Möller

apps/s_server.c

@@ -94,10 +94,6 @@ typedef unsigned int u_int;
 #undef FIONBIO
 #endif
 
-#if defined(NO_RSA) && !defined(NO_SSL2)
-#define NO_SSL2
-#endif
-
 #ifndef NO_RSA
 static RSA MS_CALLBACK *tmp_rsa_cb(SSL *s, int is_export, int keylength);
 #endif