support table([pid list]) on Linux platform

[wangvisual]

In my work environment, there are a lot of big machines with hundreds of cores and thousands of processes running on it.

So to efficiently get the processes of current session, we use cgroups etc to get a limit number of processes and then pass it to Proc::ProcessTable, the usage would be like:

my $ProcessTable = Proc::ProcessTable->new( 'enable_ttys' => 0 );
my $processes = $ProcessTable->table($Cgroups->get_active_pids())

This patch has been tested on x86_64, aarch64, and ppc64le.

Thanks.