* tests/test-dprintf-gnu.h: New file, extracted from
tests/test-dprintf-gnu.c.
* tests/test-dprintf-gnu.c: Include it.
(test_function): Remove function.
* modules/dprintf-gnu-tests (Files): Add it.
* tests/test-dzprintf-gnu.c: New file, based on
tests/test-dprintf-gnu.c.
* tests/test-dzprintf-gnu.sh: New file, based on
tests/test-dprintf-gnu.sh.
* modules/dzprintf-gnu-tests: New file.
* tests/test-dprintf-gnu.sh: New file, based on
tests/test-dprintf-posix.sh.
* tests/test-dprintf-gnu.c: New file, based on
tests/test-vasnprintf-gnu.c.
* modules/dprintf-gnu-tests: New file, based on
modules/dprintf-posix-tests.