fix typo in last commit

Author: davidmalcolm

generate-location-c.py

@@ -67,7 +67,7 @@ def generate_location():
                                    typename='PyGccLocation')
     getsettable.add_simple_getter(cu,
                                   'in_system_header',
-                                  'PyBool_FromLong(gcc_location_in_system_header_at(self->loc))',
+                                  'PyBool_FromLong(gcc_location_get_in_system_header(self->loc))',
                                   'Boolean: is this location within a system header?')
     cu.add_defn(getsettable.c_defn())