stdio-h: Work around fwrite bug in msvcrt. Reported by 松延 英樹 <maznobu@gmail.com> in <https://github.com/mlocati/gettext-iconv-windows/issues/52>. * lib/stdio.in.h (gl_consolesafe_fwrite): New declaration. (fwrite): When msvcrt is in use, use gl_consolesafe_fwrite. * lib/stdio-consolesafe.c: New file. * lib/stdio-write.c (fwrite): When msvcrt is in use, use gl_consolesafe_fwrite. * modules/stdio.h (Files): Add lib/stdio-consolesafe.c. (Depends-on): Add stdckdint-h. (configure.ac): Define condition GL_COND_OBJ_STDIO_CONSOLESAFE. (Makefile.am): Arrange to compile stdio-consolesafe.c. * doc/posix-functions/fwrite.texi: Document the workaround.