perl: include profile scripts for PATH appending

[MingcongBai]

Perl, with the Core 4 update, has a new behavior that vendor modules are installed at /usr/lib/perl5/vendor_perl and /usr/bin/vendor_perl/, which has rendered some programs unusable as our $PATH does not cover this directory.

We should include a profile script for it, something like this:

https://git.archlinux.org/svntogit/packages.git/tree/trunk/perlbin.sh?h=packages/perl

But much prettier.