Fixed compiling issues when using --disable-crypto

Fixed compiling issues when using --disable-crypto

Peter Korsgaard <jacmet@sunsite.dk> reported an issue [1] when compiling
with --disable-crypto activated.  He suggested a patch, which only
partly solved the issue.  SVN r6568 / commit 3cf9dd88fd84108 added a
new feature which further made it impossible to compile without crypto.

This patch fixes both issues, based on Peter Korsgaard's patch.

[1] <http://sourceforge.net/mailarchive/forum.php?thread_name=87fwx08bod.fsf%40macbook.be.48ers.dk&forum_name=openvpn-devel>

Signed-off-by: James Yonan <james@openvpn.net>
Acked-by: David Sommerseth <dazo@users.sourceforge.net>
Signed-off-by: David Sommerseth <dazo@users.sourceforge.net>