fabs* tests: More tests. * tests/test-fabs.h: New file, partially extracted from tests/test-fabsl.c. * tests/test-fabs.c (RANDOM): New macro. * tests/test-fabsf.c (RANDOM): New macro. * tests/test-fabsl.c (RANDOM): New macro. * modules/fabs-tests (Files): Add tests/randomd.c. (Makefile.am): Add randomd.c to test_fabs_SOURCES. * modules/fabsf-tests (Files): Add tests/randomf.c. (Makefile.am): Add randomf.c to test_fabsf_SOURCES. * modules/fabsl-tests (Files): Add tests/randoml.c. (Makefile.am): Add randoml.c to test_fabsl_SOURCES.