Fix permission-checking bug reported by Tim Burgess 10-Feb-03 (this time

for sure...).  Rather than relying on the query context of a rangetable
entry to identify what permissions it wants checked, store a full AclMode
mask in each RTE, and check exactly those bits.  This allows an RTE
specifying, say, INSERT privilege on a view to be copied into a derived
UPDATE query without changing meaning.  Per recent discussion thread.
initdb forced due to change of stored rule representation.