If opening the db in READ_ONLY give a warning if it is missing
If opening the db in READ_ONLY give a warning if it is missing

This fixes no output for pkg-rquery and pkg-clean when there
is no database.

khorben/pkg,skoef/pkg,Open343/pkg,en90/pkg,khorben/pkg,khorben/pkg,skoef/pkg,Open343/pkg,junovitch/pkg,en90/pkg,junovitch/pkg