Fix previous commit.

Fix previous commit.

 config.bat: Use autogen/config.in in one more place.
 msdos/sedlibmk.inp (GNULIB_PRINTF, GNULIB_PRINTF_POSIX): Add missing
 variables.
 (MKDIR_P): Fix replacement command.
 (NEXT_AS_FIRST_DIRECTIVE_STDIO_H, NEXT_STDIO_H): Edit to
 "<stdio.h>", as lib/stdio.h cannot be left unused.