gnu: nix: Propagate perl inputs.

* gnu/packages/package-management.scm (nix)[inputs]: Move
  perl-www-curl, perl-dbi, perl-dbd-sqlite to...
  [propagated-inputs]: ...this new field

gnu/packages/package-management.scm

@@ -200,10 +200,10 @@ (define-public nix
               ("openssl" ,openssl)
               ("libgc" ,libgc)
               ("sqlite" ,sqlite)
-              ("bzip2" ,bzip2)
-              ("perl-www-curl" ,perl-www-curl)
-              ("perl-dbi" ,perl-dbi)
-              ("perl-dbd-sqlite" ,perl-dbd-sqlite)))
+              ("bzip2" ,bzip2)))
+    (propagated-inputs `(("perl-www-curl" ,perl-www-curl)
+                         ("perl-dbi" ,perl-dbi)
+                         ("perl-dbd-sqlite" ,perl-dbd-sqlite)))
     (home-page "http://nixos.org/nix/")
     (synopsis "The Nix package manager")
     (description