Remove libhistory check

According to GNU Readline developers, if we link with libreadline then
there is no need to link with libhistory at all.

configure.ac

@@ -361,12 +361,6 @@ if test "$enable_client" = yes ; then
     [$TINFO_LIBS]
   )
 
-  AC_SEARCH_LIBS([add_history], [history readline],
-    [HISTORY_LIBS="$LIBS"; LIBS=""],
-    [AC_MSG_ERROR([The client requires GNU Readline library. Either install the library or use --disable-client to compile without the client.])],
-    [$TINFO_LIBS]
-  )
-
   AC_CHECK_LIB([readline], [rl_crlf],
     [AC_DEFINE([HAVE_RL_CRLF], [1], [Define to 1 if you have rl_crlf()])],
     [],
@@ -380,7 +374,7 @@ if test "$enable_client" = yes ; then
   )
 
   LIBS="$BASE_LIBS"
-  CLIENT_LIBS="$HISTORY_LIBS $READLINE_LIBS $TINFO_LIBS"
+  CLIENT_LIBS="$READLINE_LIBS $TINFO_LIBS"
 fi
 AC_SUBST([CLIENT])
 AC_SUBST([CLIENT_LIBS])