more information if cplus_demangle is not found

configure.in

@@ -102,7 +102,14 @@ AM_CONDITIONAL(HAVE_STACKTRACE, test "$have_stacktrace" = "yes")
 if test "$have_stacktrace" = "yes"; then
   AC_SEARCH_LIBS(cplus_demangle, [demangle iberty],
                  [AC_MSG_RESULT([OK, found cplus_demangle])],
-                 [AC_MSG_ERROR([Library iberty is required!])])
+[AC_MSG_ERROR([Function cplus_demangle not found!
+ - I looked in libdemangle and libiberty
+ - Try "ls -l /usr/lib/libdemangle* /usr/lib/libiberty*"
+    - is one of them installed?
+       - If yes, try: "nm <filename> | grep cplus_demangle"
+          -> is the symbol defined?
+ - Try to compile with option --disable-stacktrace
+   If you are not a developer, you perhaps don't need it...?])])
 fi
 AC_ARG_WITH([boost-thread],AS_HELP_STRING([--with-boost-thread],
             [specify the boost thread library or suffix to use]),