qapi.py: Decent syntax error reporting

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 1374939721-7876-5-git-send-email-armbru@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

tests/qapi-schema/test-qapi.py

@@ -16,6 +16,8 @@ import sys
 
 try:
     exprs = parse_schema(sys.stdin)
+except SystemExit:
+    raise
 except:
     print >>sys.stderr, "Crashed:", sys.exc_info()[0]
     exit(1)