fix bugs found with stricter flake8 rules

- When you don't use wildcards, flake8 will find places where you used an
  undefined name.

- This commit has all the bugfixes resulting from this static check.

var/spack/repos/builtin/packages/openfoam-com/package.py

@@ -673,9 +673,9 @@ def __init__(self, spec, **kwargs):
                 platform += 'ia64'
             elif target == 'armv7l':
                 platform += 'ARM7'
-            elif target == ppc64:
+            elif target == 'ppc64':
                 platform += 'PPC64'
-            elif target == ppc64le:
+            elif target == 'ppc64le':
                 platform += 'PPC64le'
         elif platform == 'darwin':
             if target == 'x86_64':