Change CPAN_MIRROR to the address where it resolves.

Change CPAN_MIRROR to the address where it resolves.

  "https://search.cpan.org/CPAN"  -->  "https://cpan.metacpan.org"

  Update other locations that reference search.cpan.org as appropriate.

    https://log.perl.org/2018/05/goodbye-search-dot-cpan-dot-org.html

Signed-off-by: Jason Schonberg <schonm@gmail.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>