* tests/test-vfprintf-gnu.sh: New file, based on
tests/test-vfprintf-posix.sh.
* tests/test-vfprintf-gnu.c: New file, based on
tests/test-vfprintf-posix.c.
* tests/test-fprintf-gnu.h: New file, based on
tests/test-vasnprintf-gnu.c.
* tests/test-printf-gnu.output: New file, based on
tests/test-vasnprintf-gnu.c.
* modules/vfprintf-gnu-tests: New file, based on
modules/vfprintf-posix-tests.
