Merge branch 'mplegendre-multi_pkgsrc_roots' into develop

- This moves var/spack/packages to var/spack/repos/builtin/packages.

- Packages that did not exist in the source branch, or were changed in
  develop, were moved into var/spack/repos/builtin/packages as part of
  the integration.

Conflicts:
	lib/spack/spack/test/unit_install.py
	var/spack/repos/builtin/packages/clang/package.py

var/spack/repos/builtin/packages/patchelf/package.py

@@ -0,0 +1,16 @@
+from spack import *
+
+class Patchelf(Package):
+    """PatchELF is a small utility to modify the dynamic linker and RPATH of ELF executables."""
+
+    homepage = "https://nixos.org/patchelf.html"
+    url      = "http://nixos.org/releases/patchelf/patchelf-0.8/patchelf-0.8.tar.gz"
+    list_url = "http://nixos.org/releases/patchelf/"
+    list_depth = 2
+
+    version('0.8', '407b229e6a681ffb0e2cdd5915cb2d01')
+
+    def install(self, spec, prefix):
+        configure('--prefix=%s' % prefix)
+        make()
+        make("install")