Debugger/Remote Debugging: Add "GNU target" start parameter.

This is needed for multi-architecture gdb.

Reviewed-by: hjk

src/plugins/debugger/debuggerengine.h

@@ -90,6 +90,7 @@ public:
     // for remote debugging
     QString remoteChannel;
     QString remoteArchitecture;
+    QString gnuTarget;
     QString symbolFileName;
     bool useServerStartScript;
     QString serverStartScript;