Second try at fixing libedit configuration for Bob Friesenhahn.

Buildfarm results from 'gazelle' show that there are indeed libedit
versions for which history.h is a needed header, even though it's
apparently been dropped entirely in other versions.  Grumble.

configure.in

 dnl Process this file with autoconf to produce a configure script.
-dnl $PostgreSQL: pgsql/configure.in,v 1.480 2006/10/04 22:31:13 tgl Exp $
+dnl $PostgreSQL: pgsql/configure.in,v 1.481 2006/10/05 00:07:45 tgl Exp $
 dnl
 dnl Developers, please strive to achieve this order:
 dnl
@@ -756,10 +756,12 @@ if expr x"$pgac_cv_check_readline" : 'x-ledit' >/dev/null ; then
 If you have libedit already installed, see config.log for details on the
 failure.  It is possible the compiler isn't looking in the proper directory.
 Use --without-readline to disable libedit support.])])])])
-# Note: in a libedit installation, history.h is normally a dummy, and may
-# not be there at all.  The functions are declared in readline.h instead.
-# To avoid including incompatible headers when both libraries are present,
-# assume we do not need history.h.
+# Note: in a libedit installation, history.h is sometimes a dummy, and may
+# not be there at all.  Hence, don't complain if not found.  We must check
+# though, since in yet other versions it is an independent header.
+  AC_CHECK_HEADERS(editline/history.h, [],
+        [AC_CHECK_HEADERS(history.h, [],
+                [AC_CHECK_HEADERS(readline/history.h)])])
 fi
 
 if test "$with_zlib" = yes; then

src/include/pg_config.h.in

@@ -101,6 +101,9 @@
 /* Define to 1 if you have the `dlopen' function. */
 #undef HAVE_DLOPEN
 
+/* Define to 1 if you have the <editline/history.h> header file. */
+#undef HAVE_EDITLINE_HISTORY_H
+
 /* Define to 1 if you have the <editline/readline.h> header file. */
 #undef HAVE_EDITLINE_READLINE_H