Add test for correct '\0' in dname

src/zscanner/test/processing.c

src/zscanner/test/tests/01_owner.in

src/zscanner/test/tests/01_owner.out

src/zscanner/test/tests/04-0_ORIGIN.out

src/zscanner/test/tests/06-0_INCLUDE.out

src/zscanner/test/tests/06-8_INCLUDE.out

src/zscanner/test/tests/26_SRV.out