Support for MSVC compiler: Avoid division by a literal 0.

Support for MSVC compiler: Avoid division by a literal 0.

* lib/math.in.h (NAN): Define through a function call also on MSVC.
* m4/frexp.m4 (gl_FUNC_FREXP_WORKS): Divide by 'zero' instead of 0.0.
* m4/printf.m4 (gl_PRINTF_INFINITE, gl_PRINTF_DIRECTIVE_A,
gl_PRINTF_DIRECTIVE_F, gl_PRINTF_FLAG_ZERO): Likewise.
(gl_PRINTF_INFINITE_LONG_DOUBLE): Divide by 'zeroL' instead of 0.0L.
* tests/infinity.h: New file.
* tests/nan.h (NaNf, NaNd, NaNl): Define through a function call also
on MSVC.
* tests/test-ceilf1.c: Include infinity.h.
(main): Use Infinityf.
* tests/test-ceil1.c: Include infinity.h.
(main): Use Infinityd.
* tests/test-ceill.c: Include infinity.h.
(main): Use Infinityl.
* tests/test-dprintf-posix.c: Include infinity.h.
(test_function): Use Infinityd.
* tests/test-floorf1.c: Include infinity.h.
(main): Use Infinityf.
* tests/test-floor1.c: Include infinity.h.
(main): Use Infinityd.
* tests/test-floorl.c: Include infinity.h.
(main): Use Infinityl.
* tests/test-fprintf-posix.c: Include infinity.h.
(test_function): Use Infinityd.
* tests/test-frexp.c: Include infinity.h.
(main): Use Infinityd.
* tests/test-frexpl.c: Include infinity.h.
(main): Use Infinityl.
* tests/test-isfinite.c: Include infinity.h.
(test_isfinitef): Use Infinityf.
(test_isfinited): Use Infinityd.
(test_isfinitel): Use Infinityl.
* tests/test-isinf.c: Include infinity.h.
(test_isinff): Use Infinityf.
(test_isinfd): Use Infinityd.
(test_isinfl): Use Infinityl.
* tests/test-isnan.c: Include infinity.h.
(test_float): Use Infinityf.
(test_double): Use Infinityd.
(test_long_double): Use Infinityl.
* tests/test-isnanf.h: Include infinity.h.
(main): Use Infinityf.
* tests/test-isnand.h: Include infinity.h.
(main): Use Infinityd.
* tests/test-isnanl.h: Include infinity.h.
(main): Use Infinityl.
* tests/test-ldexpl.c: Include infinity.h.
(main): Use Infinityl.
* tests/test-printf-posix.h: Include infinity.h.
(test_function): Use Infinityd.
* tests/test-roundf1.c: Include infinity.h.
(main): Use Infinityf.
* tests/test-round1.c: Include infinity.h.
(main): Use Infinityd.
* tests/test-roundl.c: Include infinity.h.
(main): Use Infinityl.
* tests/test-signbit.c: Include infinity.h.
(test_signbitf): Use Infinityf.
(test_signbitd): Use Infinityd.
(test_signbitl): Use Infinityl.
* tests/test-snprintf-posix.h: Include infinity.h.
(test_function): Use Infinityd, Infinityl.
* tests/test-sprintf-posix.h: Include infinity.h.
(test_function): Use Infinityd, Infinityl.
* tests/test-truncf1.c: Include infinity.h.
(main): Use Infinityf.
* tests/test-trunc1.c: Include infinity.h.
(main): Use Infinityd.
* tests/test-truncl.c: Include infinity.h.
(main): Use Infinityl.
* tests/test-vasnprintf-posix.c: Include infinity.h.
(test_function): Use Infinityd, Infinityl.
* tests/test-vasprintf-posix.c: Include infinity.h.
(test_function): Use Infinityd, Infinityl.
* modules/ceilf-tests (Files): Add tests/infinity.h.
* modules/ceil-tests (Files): Likewise.
* modules/ceill-tests (Files): Likewise.
* modules/dprintf-posix-tests (Files): Likewise.
* modules/floorf-tests (Files): Likewise.
* modules/floor-tests (Files): Likewise.
* modules/floorl-tests (Files): Likewise.
* modules/fprintf-posix-tests (Files): Likewise.
* modules/frexp-tests (Files): Likewise.
* modules/frexp-nolibm-tests (Files): Likewise.
* modules/frexpl-tests (Files): Likewise.
* modules/frexpl-nolibm-tests (Files): Likewise.
* modules/isfinite-tests (Files): Likewise.
* modules/isinf-tests (Files): Likewise.
* modules/isnan-tests (Files): Likewise.
* modules/isnanf-tests (Files): Likewise.
* modules/isnanf-nolibm-tests (Files): Likewise.
* modules/isnand-tests (Files): Likewise.
* modules/isnand-nolibm-tests (Files): Likewise.
* modules/isnanl-tests (Files): Likewise.
* modules/isnanl-nolibm-tests (Files): Likewise.
* modules/ldexpl-tests (Files): Likewise.
* modules/printf-posix-tests (Files): Likewise.
* modules/roundf-tests (Files): Likewise.
* modules/round-tests (Files): Likewise.
* modules/roundl-tests (Files): Likewise.
* modules/signbit-tests (Files): Likewise.
* modules/snprintf-posix-tests (Files): Likewise.
* modules/sprintf-posix-tests (Files): Likewise.
* modules/truncf-tests (Files): Likewise.
* modules/trunc-tests (Files): Likewise.
* modules/truncl-tests (Files): Likewise.
* modules/vasnprintf-posix-tests (Files): Likewise.
* modules/vasprintf-posix-tests (Files): Likewise.
* modules/vdprintf-posix-tests (Files): Likewise.
* modules/vfprintf-posix-tests (Files): Likewise.
* modules/vprintf-posix-tests (Files): Likewise.
* modules/vsnprintf-posix-tests (Files): Likewise.
* modules/vsprintf-posix-tests (Files): Likewise.
* modules/xprintf-posix-tests (Files): Likewise.