reindex creates predicate lock on index root

During testing of the SSI DDL changes I noticed that a REINDEX INDEX
created a predicate lock on page 0 of the index.  This is pretty
harmless, but mildly annoying.  There are a few other places where
it would be good to suppress predicate locks; these are listed on
the R&D section of the Wiki.  I hope to clean some of these up in
9.2. Unless a very clean and safe fix for the subject issue pops out
on further review, I'll add this to that list.
 
-Kevin