* readline/aclocal.m4: Use AC_TRY_LINK to check for mbstate_t.

	* readline/complete.c (pwd.h): Guard with HAVE_PWD_H.
	(getpwent): Guard with HAVE_GETPWENT.
	(rl_username_completion_function): Guard use of getpwent.
	(endpwent): Likewise.
	* readline/config.h.in (HAVE_FCNTL): New macro.
	(HAVE_GETPWENT): Likewise.
	(HAVE_GETPWNAM): Likewise.
	(HAVE_GETPWUID): Likewise.
	(HAVE_KILL): Likewise.
	(HAVE_PWD_H): Likewise.
	* readline/configure: Regenerated.
	* readline/configure.in: Handle MinGW when cross compiling.  Check for
	getpwnam, getpwent, getpwuid, kill, and pwd.h.
	* readline/display.c (rl_clear_screen): Treat Windows like DOS.
	(insert_some_chars): Likewise.
	(delete_chars): Likewise.
	* readline/shell.c (pwd.h): Guard with HAVE_PWD_H.
	(getpwuid): Guard with HAVE_GETPWUID.
	(sh_unset_nodelay_mode): Guard use of fnctl with HAVE_FNCTL_H.
	* readline/signals.c (rl_signal_handler): Don't use SIGALRM or
	SIGQUIT if not defined.  Use "raise" if "kill" is not available.
	(rl_set_signals): Don't set handlers for SIGQUIT or SIGALRM if
	they are not defined.
	(rl_clear_signals): Likewise.
	* readline/tilde.c (pwd.h): Guard with HAVE_PWD_H.
	(getpwuid): Guard declaration with HAVE_GETPWUID.
	(getpwnam): Guard declaration with HAVE_GETPWNAM.
	(tilde_expand_word): Guard use of getpwnam with HAVE_GETPWNAM.