db_dump.o depends on budb_errs.h

Add INCLS and budb_errs.h accordingly.

budb had this already, in 6fda61ba2e2290dac818b42440fac1346d05b73d.

Change-Id: I5ef372e8f8b9ad270b83e158d0ce14109e0f9ef1
Reviewed-on: http://gerrit.openafs.org/9996
Reviewed-by: Jeffrey Hutzelman <jhutz@cmu.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>