Set environment variables for Perl

---

examples/perl-set-environment-variables/.travis.yml

language: perl
perl:
   - "5.30"
   - "5.28"

env:
    - DEMO=Alpha

examples/perl-set-environment-variables/Makefile.PL

use strict;
use warnings;
use ExtUtils::MakeMaker;

print "$ENV{DEMO}\n";

WriteMakefile(
    NAME         => 'Project',
    AUTHOR       => q{Gabor Szabo <szabgab@cpan.org>},
    VERSION      => '0.01',
    ABSTRACT     => 'Demo Perl Makefile.PL',
    ( $ExtUtils::MakeMaker::VERSION >= 6.3002
        ? ( 'LICENSE' => 'perl' )
        : () ),
    PL_FILES  => {},
    PREREQ_PM => {
    },
    dist  => { COMPRESS => 'gzip -9f', SUFFIX => 'gz', },
);