Websocket spectrum: updated documentation

sdrbase/dsp/spectrumvis.h

@@ -43,7 +43,7 @@ namespace SWGSDRangel {
     class SWGSuccessResponse;
 };
 
-class SDRGUI_API SpectrumVis : public BasebandSampleSink {
+class SDRBASE_API SpectrumVis : public BasebandSampleSink {
 
 public:
     class SDRBASE_API MsgConfigureSpectrumVis : public Message {
@@ -87,7 +87,7 @@ public:
         { }
     };
 
-    class MsgConfigureWSpectrumOpenClose : public Message
+    class SDRBASE_API MsgConfigureWSpectrumOpenClose : public Message
     {
 		MESSAGE_CLASS_DECLARATION