use strict;
use XML::Simple;

my $data = do {local $/;<DATA>};
my $xml  = XMLin($data,forcearray=>1);
my $new;

for my $req (@{$xml->{requirement}}) {
   my %temp;
   $temp{text} = delete $req->{content};
   $temp{attributes} = [%$req];
   push @{$new->{requirements}}, {%temp};
}

__DATA__
<xml>
<requirement contactname="Joe Average">A power cord.</requirement>
<requirement contactname="Jane Smith" contactnumber="555-1212">A node name</requirement>
</xml>