Update for NetBSD 9.3 and 10.0.
* doc/*/*.texi: Update for NetBSD 9.3 and 10.0.
* m4/expm1l.m4 (gl_FUNC_EXPM1L): Update comments and cross-compilation
guess.
* m4/log1pl.m4 (gl_FUNC_LOG1PL_WORKS): Likewise.
* m4/log2l.m4 (gl_FUNC_LOG2L_WORKS): Likewise.
* m4/printf.m4 (gl_SWPRINTF_DIRECTIVE_LA): Likewise.
* m4/remainderl.m4 (gl_FUNC_REMAINDERL_WORKS): Likewise.
* m4/fcntl.m4: Update comments.
* m4/fenv-environment.m4: Likewise.
* m4/fenv-exceptions-trapping.m4: Likewise.
* m4/fnmatch.m4: Likewise.
* m4/getcwd-abort-bug.m4: Likewise.
* m4/iswdigit.m4: Likewise.
* m4/iswxdigit.m4: Likewise.
* m4/modfl.m4: Likewise.
* m4/wcscmp.m4: Likewise.
* m4/wcsncmp.m4: Likewise.
* m4/wctrans.m4: Likewise.
* m4/wcwidth.m4: Likewise.