frexp* tests: More tests.

frexp* tests: More tests.

* tests/test-frexp.h (test_function): Add some pseudo-randomized tests.
* tests/test-frexp.c (RANDOM): New macro.
* tests/test-frexpf.c (RANDOM): New macro.
* tests/test-frexpl.c (RANDOM): New macro.
* modules/frexp-tests (Files): Add tests/randomd.c.
(Makefile.am): Add randomd.c to test_frexp_SOURCES.
* modules/frexpf-tests (Files): Add tests/randomf.c.
(Makefile.am): Add randomf.c to test_frexpf_SOURCES.
* modules/frexpl-tests (Files): Add tests/randoml.c.
(Makefile.am): Add randoml.c to test_frexpl_SOURCES.