First part of fix for #493826: if 'errn' key exists in return value this doesn't…

First part of fix for #493826: if 'errn' key exists in return value this doesn't necesarily signal an error, only if the value is non-zero it does. This
does not correspond with my reading of the documentation, but the OSX Finder can return 'errn'=0, and it knows better than me:-)

Bugfix candidate.

Mac/scripts/gensuitemodule.py

@@ -498,7 +498,7 @@ def compileevent(fp, event, enumsneeded):
 	#
 	# Error handling
 	#
-	fp.write("\t\tif _arguments.has_key('errn'):\n")
+	fp.write("\t\tif _arguments.get('errn', 0):\n")
 	fp.write("\t\t\traise aetools.Error, aetools.decodeerror(_arguments)\n")
 	fp.write("\t\t# XXXX Optionally decode result\n")
 	#