DB and DBCompat

[Bradley Baetz]

My intention (not that its gone anywhere, given the limited time I've
had to spend on Bugzilla recently) was for the dbcompat module to
contain the bits which need to be explicitly used for cross-db support
within string concatentation (eg SqlDate), but to leave the other stuff
in Bugzilla::Db, overridden by Bugzilla::DB::mysql/Pg/etc transparently
(eg connect).

I'm not sure that connect needs to be overloaded, however - all that we
need is the DBD name, and DBI takes care of the rest, in theory.

I'm not too sure how realistic that is, though. Maybe we need to make a
list of what sort of stuff we need in the compat module.

Bradley