Update C::AC check as meant ...

http://images.thewirelesscatalog.com/graphics/products/regular/VP5272.jpg :)

Though the use of Dist::Zilla - where I'm not very familiar with - I couldn't test my changes:
$ dzil run $SHELL
[DZ] building distribution under .build/dnvnAR8RL7 for installation
[DZ] beginning to build File-LibMagic
[DZ] guessing dist's main_module is lib/File/LibMagic.pm
  1 Update bundled Config::AutoConf
[DZ] extracting distribution abstract from lib/File/LibMagic.pm
[@DROLSKY/GitHub::Meta] Getting GitHub repository info
[@DROLSKY/ExtraTests] rewriting release test xt/release/pod-coverage.t
  1 try to use modern way to check for libmagic
[@DROLSKY/ExtraTests] rewriting author test xt/author/pod-spell.t
[@DROLSKY/ExtraTests] rewriting release test xt/release/pod-syntax.t
[@DROLSKY/ExtraTests] rewriting release test xt/release/cpan-changes.t
[@DROLSKY/ExtraTests] rewriting author test xt/author/eol.t
[@DROLSKY/ExtraTests] rewriting author test xt/author/no-tabs.t
[@DROLSKY/ExtraTests] rewriting release test xt/release/pod-linkcheck.t
[@DROLSKY/ExtraTests] rewriting release test xt/release/portability.t
[@DROLSKY/ExtraTests] rewriting release test xt/release/synopsis.t
[@DROLSKY/ReadmeMarkdownInBuild] someone tried to munge lib/File/LibMagic.pm after we read from it. Making modifications again...
[DZ] writing File-LibMagic in .build/dnvnAR8RL7
[@DROLSKY/ReadmeMarkdownInRoot] overriding README.md in root
Checking for library containing magic_open... no

  This module requires the libmagic.so library and magic.h header. See
  INSTALL.md for more details on installing these.

make: *** No targets specified and no makefile found.  Stop.
[DZ] error running make

It doesn't use the local inc/MyMakeMaker.pm ...

I tried to port the check from https://github.com/i-scream/Unix-Statgrab as good as possible together with the workaround for broken file checks from MakeMaker ...
With some help I might be able to provide a tested code-piece and an update for Params-Validate doing fine cross-compiling ;)

Cheers,
Jens