Elemental fix (#5067)

* Added a package for the MDAnalysis toolkit.

* Added additional packages that Elemental depends on.

* Changed LBANN to not ask for the scalapack variant in Elemental.

* Removed variant control on scalapack

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

@@ -87,6 +87,9 @@ class Elemental(CMakePackage):
     depends_on('scalapack', when='+scalapack ~int64_blas')
     extends('python', when='+python')
     depends_on('python@:2.8', when='+python')
+    depends_on('gmp')
+    depends_on('mpc')
+    depends_on('mpfr')
 
     patch('elemental_cublas.patch', when='+cublas')