[master] 7812674 really bail out if no usable readline found

[Nils Goroll]

commit 78126742bfa3831959b3cbb3e8ff58e45ff49dd6
Author: Nils Goroll <nils.goroll at uplex.de>
Date:   Fri Jul 25 15:31:04 2014 +0200

    really bail out if no usable readline found
    
    Fixes #1555

diff --git a/configure.ac b/configure.ac
index ced8495..3c35abd 100644
--- a/configure.ac
+++ b/configure.ac
@@ -142,7 +142,7 @@ AC_SUBST(PCRE_LIBS)
 PKG_CHECK_MODULES([LIBEDIT], [libedit], 
 	[AC_DEFINE([HAVE_LIBEDIT], [1], [Define we have libedit])],
 	[AX_LIB_READLINE])
-if test "$ac_cv_have_readline" = no; then
+if test "x$ac_cv_have_readline" != xyes; then
   AC_MSG_ERROR([libedit or readline not found])
 fi