VMS: simplify config targets

All VMS config targets were literally copies of each other, only
differing in what argument the parameter seeking function vms_info()
received (the pointer size).

This could be hugely simplified by letting vms_info() detect what
pointer size was desired from the desired config target name instead.

Reviewed-by: Andy Polyakov <appro@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5364)