* tests/factor/factor.pl: Verify that embedded NULs
on stdin terminate the _number_.
* tests/numfmt/numfmt.p: Verify that embedded NULs
on stdin terminate the _line_.
https://github.com/coreutils/coreutils/pull/196
* tests/numfmt/mb-non-utf8.sh: Test GB18030 delimiter search.
* tests/local.mk: Reference the new test, and move
the existing numfmt.pl test from tests/misc to tests/numfmt.