Make HAVE_TERMIOS_H and associated config.sh shell variable available
when configure detects the presence of termios.h; later we'll use this
for correct configuration of edline/readline.

Also, fix a bug in acconfig.h -- somebody forgot to add an undef to
cover the LIBNDBM configure symbol, which was preventing autoheader
from working properly.
diff --git a/configure.in b/configure.in
index 8fa11e8..61dead1 100644
--- a/configure.in
+++ b/configure.in
@@ -406,7 +406,7 @@
 # checks for header files
 AC_HEADER_STDC
 AC_CHECK_HEADERS(dlfcn.h fcntl.h limits.h locale.h ncurses.h poll.h pthread.h \
-signal.h stdarg.h stddef.h stdlib.h thread.h unistd.h utime.h \
+signal.h stdarg.h stddef.h stdlib.h thread.h unistd.h utime.h termios.h \
 sys/audioio.h sys/file.h sys/lock.h db_185.h db.h \
 sys/param.h sys/select.h sys/socket.h sys/time.h sys/times.h \
 sys/un.h sys/utsname.h sys/wait.h pty.h libutil.h \