[RFC] perl prerequiste

Hello!

Makefile.PL/ExtUtils::MakeMaker has no way to specify required perl 
version except "use 5.006;".
I propose to make possible to specify perl version same way as in Build.PL.
Ex.:
'PREREQ_PM'     => {
    perl => 5.006,
},

It should also be in META.yml. In future smart install shell should be 
able to determine which version of module to install by downloading only 
META.yml.


Attached is first patch. It skips 'perl' when trying to load 
prerequisites from PREREQ_PM (but not when writing META.yml). All tests 
pass.

-- 
WBR,
  Alexandr                          mailto:[email protected]

--- MakeMaker.pm.dist	Tue Jul  3 11:08:31 2007
+++ MakeMaker.pm	Thu Oct 11 17:11:10 2007
@@ -400,6 +400,7 @@
 
     my(%unsatisfied) = ();
     foreach my $prereq (sort keys %{$self->{PREREQ_PM}}) {
+        next if $prereq eq 'perl';
         # 5.8.0 has a bug with require Foo::Bar alone in an eval, so an
         # extra statement is a workaround.
         my $file = "$prereq.pm";