Adapt mk1mf.pl and helpers to the new testing framework.

With the new testing framework, building a test target with mk1mf.pl
becomes a very simple thing.  And especially, no more need to do the
amount of hackery in unix.pl we did.

Also, some tests need a working apps/CA.pl as well as rehashed certs
in certs/demo.  So, move the code creating those files so it gets done
regardless, not just in non-mk1mf environments.

Reviewed-by: Rich Salz <rsalz@openssl.org>