This will give one an idea of the degree of confusion out in the field regarding this subject.

I Googled "$Config{randfunc} drand48".

I got three hits on this fellow's GitHub.

The code below is from https://github.com/drzigman/perl-random/blob/master/drand48/driver_perl/generate.pl

use Config;

# Make sure we are using drand48 as the underlying implementation
if($Config{randfunc} ne "drand48") {
    print "Perl is configured with randfunc '" . $Config{randfunc}
        . "' rather than drand48\n";
    return 1;
}
[download]

This code won't work anymore.

'Perl_drand48' is stored in $Config{randfunc}.