Re-add list_url for all R packages (#6110)

* r-igraph: find old packages in the archive

Fixes #6104.

* r-irlba: find old packages in the archive

Fixes #6101.

* r-lazyeval: find old packages in the archive

Fixes #6102.

* packages: set list_url for all packages hosted on CRAN

* packages: consistently use the CRAN archive URLs

var/spack/repos/builtin/packages/r-zoo/package.py

@@ -34,6 +34,7 @@ class RZoo(RPackage):
 
     homepage = "http://zoo.r-forge.r-project.org/"
     url      = "https://cran.r-project.org/src/contrib/zoo_1.7-14.tar.gz"
+    list_url = "https://cran.r-project.org/src/contrib/Archive/zoo"
 
     version('1.7-14', '8c577a7c1e535c899ab14177b1039c32')
     version('1.7-13', '99521dfa4c668e692720cefcc5a1bf30')