Remove support for broken <wchar.h> in BSD/OS and OSF/1.

Remove support for broken <wchar.h> in BSD/OS and OSF/1.

* lib/wchar.in.h: Don't include <stdio.h>, <time.h>.
* lib/mbchar.h: Likewise.
* lib/mbiter.h: Likewise.
* lib/mbuiter.h: Likewise.
* m4/stdint.m4 (gl_STDINT_INCLUDES): Likewise.
* lib/mbfile.h: Don't include <time.h>.
* lib/mbswidth.h: Update comment.
* lib/stdint.in.h: Don't include <stddef.h>, <stdio.h>, <time.h> before
<wchar.h>.
* lib/wctype.in.h: Likewise.
* m4/btowc.m4 (gl_FUNC_BTOWC): Simplify test programs.
* m4/iswblank.m4 (gl_FUNC_ISWBLANK): Likewise.
* m4/iswdigit.m4 (gl_FUNC_ISWDIGIT): Likewise.
* m4/iswxdigit.m4 (gl_FUNC_ISWXDIGIT): Likewise.
* m4/mbrlen.m4 (gl_FUNC_MBRLEN, gl_MBRLEN_INCOMPLETE_STATE,
gl_MBRLEN_RETVAL, gl_MBRLEN_NUL_RETVAL): Likewise.
* m4/mbrtoc32.m4 (gl_MBRTOC32_SANITYCHECK): Likewise.
* m4/mbrtowc.m4 (gl_FUNC_MBRTOWC, gl_MBRTOWC_INCOMPLETE_STATE,
gl_MBRTOWC_SANITYCHECK, gl_MBRTOWC_NULL_ARG1, gl_MBRTOWC_NULL_ARG2,
gl_MBRTOWC_RETVAL, gl_MBRTOWC_NUL_RETVAL, gl_MBRTOWC_STORES_INCOMPLETE,
AC_FUNC_MBRTOWC): Likewise.
* m4/mbsinit.m4 (gl_FUNC_MBSINIT): Likewise.
* m4/mbsnrtowcs.m4 (gl_MBSNRTOWCS_WORKS_IN_TRADITIONAL_LOCALE):
Likewise.
* m4/mbsrtowcs.m4 (gl_FUNC_MBSRTOWCS, gl_MBSRTOWCS_WORKS): Likewise.
* m4/mbstate_t.m4 (AC_TYPE_MBSTATE_T): Likewise.
* m4/mbswidth.m4 (gl_MBSWIDTH): Likewise.
* m4/printf.m4 (gl_PRINTF_DIRECTIVE_LS): Likewise.
* m4/wchar_h.m4 (gl_WCHAR_H, gl_WCHAR_H_INLINE_OK): Likewise.
* m4/wcrtomb.m4 (gl_FUNC_WCRTOMB): Likewise.
* m4/wcsdup.m4 (gl_FUNC_WCSDUP): Likewise.
* m4/wcsnrtombs.m4 (gl_WCSNRTOMBS_WORKS_IN_TRADITIONAL_LOCALE):
Likewise.
* m4/wcsrtombs.m4 (gl_FUNC_WCSRTOMBS, gl_WCSRTOMBS_TERMINATION,
gl_WCSRTOMBS_NULL): Likewise.
* m4/wcstok.m4 (gl_FUNC_WCSTOK): Likewise.
* m4/wctob.m4 (gl_FUNC_WCTOB): Likewise.
* m4/wctype_h.m4 (gl_WCTYPE_H): Likewise.
* m4/wcwidth.m4 (gl_FUNC_WCWIDTH): Likewise.
* m4/wint_t.m4 (gt_TYPE_WINT_T): Likewise.
* m4/wmemchr.m4 (gl_FUNC_WMEMCHR): Likewise.
* m4/wmemcmp.m4 (gl_FUNC_WMEMCMP): Likewise.
* m4/wmemcpy.m4 (gl_FUNC_WMEMCPY): Likewise.
* m4/wmemmove.m4 (gl_FUNC_WMEMMOVE): Likewise.
* m4/wmemset.m4 (gl_FUNC_WMEMSET): Likewise.