$ cat -vet pm_1070943_CRLF.txt
text^M$

$ cat -vet pm_1070943_LF.txt
text$

##</code><code>##

#!/usr/bin/env perl

use 5.010;
use strict;
use warnings;
use autodie;

for my $file (qw{pm_1070943_CRLF.txt pm_1070943_LF.txt}) {
    open my $fh, '<', $file;
    my $first_line = <$fh>;
    $first_line =~ /(\R)\z/;

    if ($1 eq "\x0D\x0A") {
        say "Skipping: $file";
    }
    else {
        say "Processing: $file";
    }
}

##</code><code>##

Skipping: pm_1070943_CRLF.txt
Processing: pm_1070943_LF.txt