Fix the DJGPP port

Fix the DJGPP port

* config.bat:
* msdos/sed1v2.inp:
* msdos/sed2v2.inp:
* msdos/sed3v2.inp:
* msdos/sedlibmk.inp: Update for Emacs 28.
* msdos/langinfo.h: New file.

* lisp/loadup.el: Use correct path to temacs when dumping on
MS-DOS.
* src/callproc.c (environ) [MSDOS]: New declaration.
(child_setup, emacs_spawn): Update MS-DOS parts for Emacs 28.
* src/fileio.c (Fcopy_file): Don't use copy_file_range on
MS-DOS.
* src/msdos.c (initialize_msdos_display): Add
`defined_color_hook'.
(openat, fchmodat, futimens, utimensat): New functions.

* src/msdos.h (FRAME_X_DISPLAY): New macro.
* src/process.c: Make some more things conditional on
subprocess support.
(PIPECONN_P, PIPECONN1_P) [!subprocesses]: New placeholder
macros.
(Fnum_processors): Return 1 on MSDOS.
(open_channel_for_module): Avoid subprocess specific code
on MSDOS.