OpenSSL-1-1-1 support

[sumantgupta1984]

This patch provides support for compiling libEST for OpenSSL-1.1.1

Please have a review of following items as i am unclear about this:

1. Could not find equivalent in OpenSSL 1.1.1 for NETSCAPE_X509 ,so disabled the support in example/server/ossl_srv.c.
2. Also at some places i see the code "req->req_info->enc.modified = 1 " where we have set the modified bit,i could not find an equivalent. If anybody finds the workaround,please update.
   3.Could not find the replacement for c2i_ASN1_OBJECT ,so converted to d2i_ASN1_OBJECT.
   Could not find any equivalent,so replaced this . Please see if its ok.

I have tested the example client/server on OpenSSL 1.1.1 and it works fine.

[sumantgupta1984]

a

[csosto-pk]

Thanks for this @sumantgupta1984 .
We have added OpenSSL 1.1.1 support and we will include it in the upcoming release of libest in a month or so.