my @unsorted = ('-6h0m','+11h39m','+1h7m','-12h8m');

my @sorted =
    map  {$_->[0]}
    sort {$b->[1] <=> $a->[1]}
    map  { /^([+-])(\d+)h(\d+)m$/; [$_, sprintf("%s%d",$1, $2*60+$3) ] }
    @unsorted;

print join ', ', @sorted;