Add `jemalloc` as dependency for NEST

packages/nest/package.py

@@ -75,6 +75,8 @@ class Nest(CMakePackage):
             description="Enable direct reading of connectivity from SONATA files")
     variant('boost',    default=True,
             description="Enable optimizations provided via Boost library algorithms and containers")
+    variant('jemalloc', default=True,
+            description="Pull in jemalloc as run-time dependency.")
     # TODO add variants for neurosim and music when these are in spack
 
     conflicts('~gsl', when='@:2.10.99',
@@ -99,6 +101,7 @@ class Nest(CMakePackage):
     depends_on('hdf5+cxx+mpi',      when='@3.4.99:+sonata+mpi', type=('build', 'run'))
     depends_on('hdf5+cxx~mpi',      when='@3.4.99:+sonata~mpi', type=('build', 'run'))
     depends_on('py-pandas',         when='@3.4.99:+sonata', type=('build', 'run'))
+    depends_on('jemalloc',          when='@3:+jemalloc', type=('run', 'test'))
 
     depends_on('py-nose',           when='@:2.99.99+python+testsuite', type='test')
     depends_on('py-pytest',         when='@3.0:+testsuite', type='test')