Adjust rpmdb path for all remaining non-fakeroot runs

Adjust rpmdb path for all remaining non-fakeroot runs
- Executing rpmbuild in the fakeroot gets fairly tricky, especially
  for the tests that actually compile things. Overriding the dbpath
  prevents it from accessing system rpmdb for keyring and build-requires.
- With this patch, the test-suite now passes the smoke-test of
  "chmod go-rx /var/lib/rpm" on system rpmdb.