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-reshape2/package.py

@@ -31,6 +31,7 @@ class RReshape2(RPackage):
 
     homepage = "https://github.com/hadley/reshape"
     url      = "https://cran.r-project.org/src/contrib/reshape2_1.4.2.tar.gz"
+    list_url = "https://cran.r-project.org/src/contrib/Archive/reshape2"
 
     version('1.4.2', 'c851a0312191b8c5bab956445df7cf5f')
     version('1.4.1', '41e9dffdf5c6fa830321ac9c8ebffe00')