Fix the MS-DOS build

Fix the MS-DOS build

* config.bat: Add assert.in-h.
* msdos/sed2v2.inp: Define HAVE_STDBOOL_H.
* msdos/sedlibmk.inp (GL_GNULIB_LCHMOD, HAVE_LCHMOD): Define to
reflect realities.
(NEXT_ASSERT_H, @GL_GENERATE_ASSERT_H_CONDITION@): Define.
(assert.h): Edit command group into individual commands appending
to assert.h-t.