Refactor frexp*-ieee tests.

Refactor frexp*-ieee tests.

* tests/test-frexp-ieee.h: New file.
* tests/test-frexpf-ieee.c: Include test-frexp-ieee.h.
(main): Just call test_function.
* tests/test-frexp-ieee.c: Include test-frexp-ieee.h.
(main): Just call test_function.
* tests/test-frexpl-ieee.c: Include test-frexp-ieee.h.
(main): Just call test_function.
* modules/frexpf-ieee-tests (Files): Add tests/test-frexp-ieee.h.
* modules/frexp-ieee-tests (Files): Likewise.
* modules/frexpl-ieee-tests (Files): Likewise.