VMS fix: link shared libs from objects files instead of from static libs

The simplifications that were made when Makefile.shared was removed
didn't work quite right.  Also, this is what we do on Unix and Windows
anyway, so this makes us more consistent across all platforms.

Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4982)