Rework building: adapt some scripts

The platform module collection is made in such a way that any Perl
script that wants to take part of the available information can use
them just as well as the build system.

This change adapts test/recipes/90-test_shlibload.t, util/mkdef.pl,
and util/shlib_wrap.sh.in

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/7473)