Remove mention of the old -X command line switch.

Misc/Porting

@@ -31,8 +31,7 @@ target platform.  Forget about the posix module for now -- simply take
 it out of the config.c file.
 
 Bang on it until you get a >>> prompt.  (You may have to disable the
-importing of "site.py" and "exceptions.py" by passing -X and -S
-options.
+importing of "site.py" by passing the -S options.)
 
 Then bang on it until it executes very simple Python statements.