Perl build system

[Ludovic Courtès]

Hello,

Commit 08fd1eb adds ‘perl-build-system’, which allows packages using the
‘perl Makefile.PL’ method to be trivially defined (not that I was eager
to do more Perl, but it turns out to be useful ;-)).

This gives a simple example of a build system built on top of
‘gnu-build-system’.

Comments welcome.

Ludo’.