Add a platform specific configuration checker

For each platform, we may need to perform some basic checks to see
that available tools perform as we expect them.

For the moment, the added checkers test that Perl gives the expected
path format.  This should help MingW users to see if they run an
appropriate Perl implementation, for example.

Reviewed-by: Andy Polyakov <appro@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2851)
(cherry picked from commit d192a3aa)