Clarified configuration and license aspects of libreadline and libedit

configure.ac

@@ -143,20 +143,26 @@ dnl The X= in the yes case prevents that -lreadline gets linked twice
     fi
 else
     READLINE_DEF=
+    echo "disabled libreadline"
 fi
 if test x$READLINE_DEF = x; then
+    if test x$enable_libreadline = xyes; then
+        libedit_deflt=yes
+    else
+        libedit_deflt=no
+    fi
     AC_ARG_ENABLE(libedit,
-    [  --enable-libedit    Enable use of libedit by xorriso if not libreadline, default=yes],
-                   , enable_libedit=yes)
+[  --enable-libedit        Enable use of libedit by xorriso if not libreadline,
+                          default= setting of --enable-libreadline],
+                   , enable_libedit=$libedit_deflt)
     if test x$enable_libedit = xyes; then
-dnl Check whether there is development and runtime support.
-dnl If not, erase this macro which would enable use of el_*(), history*()
         READLINE_DEF="-DXorriso_with_editlinE"
 
         LIBBURNIA_ASSERT_EDITLINE
 
     else
         READLINE_DEF=
+        echo "disabled libedit"
     fi
 fi
 AC_SUBST(READLINE_DEF)