repack_all_database can return an error message: in case of any error different
from "missing schema" return the error and keep processing the other databases
instead of printing and stopping the program.
The output of the program is now something like:
$ pg_reorg --all
pg_reorg: reorg database "contrib_regression"
pg_reorg: reorg database "template1" ... skipped: pg_reorg is not installed in the database
