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-pryr/package.py

@@ -32,6 +32,7 @@ class RPryr(RPackage):
 
     homepage = "https://github.com/hadley/pryr"
     url      = "https://cran.r-project.org/src/contrib/pryr_0.1.2.tar.gz"
+    list_url = "https://cran.r-project.org/src/contrib/Archive/pryr"
 
     version('0.1.2', '66b597a762aa15a3b7037779522983b6')