DSPSpy: Fix build failures

- Remove dangling #endif include guard from #pragma once conversion
- Enable C++0x support for nullptr support

Source/DSPSpy/Makefile

@@ -33,7 +33,7 @@ INCLUDES	:=	include ../Core/Common .
 #---------------------------------------------------------------------------------
 
 CFLAGS	= -save-temps -O2 -Wall --no-strict-aliasing $(MACHDEP) $(INCLUDE)
-CXXFLAGS	=	$(CFLAGS)
+CXXFLAGS	=	-std=c++0x $(CFLAGS)
 
 LDFLAGS	=	-g $(MACHDEP) -Wl,-Map,$(notdir $@).map
 

Source/DSPSpy/dsp_interface.h

@@ -32,5 +32,3 @@ public:
 	// the implementation does nothing but calling the virtual methods above.
 	void SendTask(void *addr, u16 iram_addr, u16 len, u16 start);
 };
-
-#endif  // _DSP_INTERFACE_H