Filter out perl from listdeps --omit-core

[Leont]

This will filter out perl from listed dependencies when --omit-core satisfies the requirement.

E.g. previously dzil listdeps --json --omit-core=5.042 would look something like:

{
   "configure" : {
      "requires" : {
         "perl" : "v5.13.7"
      }
   },
   "develop" : {
      "requires" : {
         "Crypt::Argon2" : "0",
         "Crypt::Bcrypt" : "0",
         "Test::Pod" : "1.41"
      }
   },
   "runtime" : {
      "requires" : {
         "Crypt::SysRandom" : "0",
         "perl" : "v5.13.7"
      }
   },
   "test" : {
      "requires" : {
         "perl" : "5.006"
      }
   }
}

that will now look like:

{
   "develop" : {
      "requires" : {
         "Crypt::Argon2" : "0",
         "Crypt::Bcrypt" : "0",
         "Test::Pod" : "1.41"
      }
   },
   "runtime" : {
      "requires" : {
         "Crypt::SysRandom" : "0"
      }
   }
}

[karenetheridge]

This would be a handy option to use on the PrereqSource role -- when finalizing all prereqs, omit those that are in core as of the minimum required perl version.

[Grinnz]

Looks like someone had that idea as part of their plugin: https://metacpan.org/pod/Dist::Zilla::Plugin::PrereqsClean

I think it would make sense as an AutoPrereqs option, but otherwise, prefer to do that determination in my manual prereq specification.

(anyway getting a bit off topic for this PR)

[karenetheridge]

yeah, filtering it in AutoPrereqs sounds fine.

[Leont]

anyway getting a bit off topic for this PR

Yeah, kind of.