Adapt Windows port to recent changes in autogen/config.in.

Adapt Windows port to recent changes in autogen/config.in.

* lib-src/makefile.w32-in (CONFIG_H): Update dependencies.
(CONF_POST_H): New macro.

* lib/makefile.w32-in (CONFIG_H): Update dependencies.
(CONF_POST_H): New macro.

* nt/config.nt: Sync with autogen/config.in.
Remove code moved to conf_post.h and include <conf_post.h>
(NULL_DEVICE, SEPCHAR, SIGNAL_H_AHB, TIOCSIGSEND, USER_FULL_NAME)
(USG5_4, WRETCODE, _longjmp, _setjmp, wait3): New macros.

* src/makefile.w32-in (CONFIG_H): Update dependencies.
(CONF_POST_H): New macro.

* src/s/ms-w32.h (SEPCHAR, NULL_DEVICE): Remove; moved to nt/config.nt.