Your problem is that the output from perl -c is going to STDERR. Try this if your shell supports this type of redirection:

my $rc = `$^X -c $_ 2>&1`;

chomp $rc;

unless ($rc eq "$_ syntax OK") {
    print "$rc";
    $errors++;
}
[download]

This is explained in qx/STRING/ in perlop.

Otherwise you could examine the value of $? after using the backticks, see perlvar:

my $rc = `$^X -c $_`;

if ($?) {
    print "$rc";
    $errors++;
}
[download]

--
John.