attcacheoff fixed, possible dump/reload

In the old system, many tables did not have an initial attcacheoff value
of -1, especially system tables.  It would have a value of zero, and
this is a valid offset for the first field.

I have fixed it so they are all -1.  With the new code that uses
attcacheoff more, you may need to do a dump/reload.  I am not sure.

-- 
Bruce Momjian
maillist@candle.pha.pa.us