Allow arbitrary levels of analyze/rewriting

Hi,

This patch will allow arbitrary levels of analyze / rewriting
by making the static variables extra_before and extra_after
automatic so we can use recursion.

It gets much easier to generate extra commands now, and one can rest
assured that the extra commands will be properly analyzed/rewritten.

Without this patch, if a command produced by transformation tries to
use these static lists their first contents would be lost with
unpredictable results. I know I could fix this by just using nconc()
instead of assignments, but the resulting order of the commands would
not be exactly what one could expect.

--
Fernando Nasser
Red Hat Canada Ltd. E-Mail: fnasser(at)redhat(dot)com
2323 Yonge Street, Suite #300
Toronto, Ontario M4P 2C9