Adapt MSDOS port to latest changes.

Adapt MSDOS port to latest changes.

 config.bat: Copy lib/execinfo.in.h to lib/execinfo.in-h if needed.

 msdos/sedlibmk.inp: Sync with changes in lib/Makefile.in.
 (HAVE_DECL_ENVIRON, GNULIB_ENVIRON): Edit to require declaration
 through lib/unistd.h.
 msdos/sed1v2.inp: Sync with changes in src/Makefile.in.
 msdos/sed2v2.inp: Sync with changes in src/config.in.

 src/lisp.mk: Adjust comments to the fact that term/internal is now
 loaded from loadup.el.
 src/msdos.c (msdos_abort): Rename from emacs_abort, and make static.
 (msdos_fatal_signal): New function.
 (XMenuActivate): Adjust the call to kbd_buffer_events_waiting to
 its argument list.
 src/conf_post.h (_GL_EXECINFO_INLINE) [MSDOS]: Define to "inline"
 for GCC versions before 4.
 (emacs_raise): Define to call msdos_fatal_signal.

 lisp/term/pc-win.el: Don't load term/internal from here.
 lisp/loadup.el: Load term/internal from here.