VMS: pretend to use -znodelete

VMS only unloads shared libraries at process rundown, so tell the
OpenSSL code so by pretending we linked with -znodelete.
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1862)

Configurations/10-main.conf

@@ -1767,6 +1767,7 @@ sub vms_info {
         cflags           => picker(default => "/STANDARD=(ISOC94,RELAXED)/NOLIST/PREFIX=ALL",
                                    debug   => "/NOOPTIMIZE/DEBUG",
                                    release => "/OPTIMIZE/NODEBUG"),
+        defines          => add("OPENSSL_USE_NODELETE"),
         lflags           => picker(default => "/MAP",
                                    debug   => "/DEBUG/TRACEBACK",
                                    release => "/NODEBUG/NOTRACEBACK"),