Warn if an extended value string falls back to linear search.

See https://www.wireshark.org/lists/wireshark-dev/201303/msg00179.html

svn path=/trunk/; revision=48415

epan/value_string.c

@@ -318,6 +318,8 @@ _match_strval_ext_init(const guint32 val, const value_string_ext *a_vse)
     if ((type == VS_BIN_TREE) &&
         ((prev_value > vs_p[i].value) || (first_value > vs_p[i].value))) {
       type = VS_SEARCH;
+      g_warning("Extended value string %s forced to fall back to linear search",
+              vse->_vs_name);
       break;
     }