change way of getting a CPEALFactref name

this breaks build now, but it reliably demonstrates the problem which needs to be fixed - handling of underscores in platform names

ssg/build_cpe.py

@@ -214,7 +214,7 @@ def __init__(self, expression, algebra, cpe_products):
 
     def _replace_cpe_names(self, exp):
         if isinstance(exp, CPEALFactRef):
-            exp.cpe_name = self.cpe_products.get_cpe_name(str(exp.obj))
+            exp.cpe_name = self.cpe_products.get_cpe_name(exp.name)
         else:
             for arg in exp.args:
                 self._replace_cpe_names(arg)