ocotpus and arpack-ng: fix arpack bug and add libs to arpack-ng (#3875)

* ocotpus and arpack-ng: fix arpack bug and add libs to arpack-ng

also rename the variant to be consistent with other packages

* fix a bug

* flake8

var/spack/repos/builtin/packages/arpack-ng/package.py

@@ -80,6 +80,19 @@ class ArpackNg(Package):
 
     depends_on('mpi', when='+mpi')
 
+    @property
+    def libs(self):
+        # TODO: do we need spec['arpack-ng:parallel'].libs ?
+        # query_parameters = self.spec.last_query.extra_parameters
+        libraries = ['libarpack']
+
+        if '+mpi' in self.spec:
+            libraries = ['libparpack'] + libraries
+
+        return find_libraries(
+            libraries, root=self.prefix, shared=True, recurse=True
+        )
+
     @when('@3.4.0:')
     def install(self, spec, prefix):
 
@@ -114,7 +127,7 @@ def install(self, spec, prefix):
             make('test')
         make('install')
 
-    @when('@3.3.0')
+    @when('@3.3.0')  # noqa
     def install(self, spec, prefix):
         # Apparently autotools are not bootstrapped
         which('libtoolize')()