Synced PseudoPerldoc process() code with Pod::Perldoc >= 3.21_01

This commit reverted changes of r19825 (commented out failing code)

Patch previously was submitted to [Padre maillist](http://mail.perlide.org/pipermail/padre-dev/2014-April/003593.html)
Note that will break with perl <= 5.18 (or so). On Debian, I've applied this:
```
my $sub =  $self->can('maybe_extend_searchpath') || $self->can('maybe_diddle_INC');
$self->$sub();
```