3235. [func] dns_db_diffx, a extended dns_db_diff which returns

                        the generated diff and optionally writes it to a
                        journal. [RT #26386]

lib/dns/tests/testdata/diff/zone1.data

+@ 	0	SOA . . 0 0 0 0 0
+@	0	NS @
+@	0	A 1.2.3.4
+remove	0	A 5.6.7.8

lib/dns/tests/testdata/diff/zone2.data

+@ 	0	SOA . . 0 0 0 0 0
+@	0	NS @
+@	0	A 1.2.3.4
+remove	0	A 5.6.7.8
+added	0	A 5.6.7.8

lib/dns/tests/testdata/diff/zone3.data

+@ 	0	SOA . . 0 0 0 0 0
+@	0	NS @
+@	0	A 1.2.3.4