Debugger: Infrastructure for reworked native mixed debugging

- Remove old experimental native mixed approach.
- Move some common stack parsing to Stackhandler.
- Mark gdbbridge.py debug output explicitly to remove it
  from actual reponse handling

New native mixed needs QtDeclarative changes and
QTC_DEBUGGER_NATIVE_MIXED=1 for now.

Change-Id: I09eed1da51cea878636d36756015b7bfaed34203
Reviewed-by: Christian Stenger <christian.stenger@theqtcompany.com>

src/plugins/debugger/watchdata.cpp

@@ -392,8 +392,8 @@ void WatchData::updateValue(const GdbMi &item)
 {
     GdbMi value = item["value"];
     if (value.isValid()) {
-        int encoding = item["valueencoded"].toInt();
-        setValue(decodeData(value.data(), DebuggerEncoding(encoding)));
+        DebuggerEncoding encoding = debuggerEncoding(item["valueencoded"].data());
+        setValue(decodeData(value.data(), encoding));
     } else {
         setValueNeeded();
     }