Fix compile errors

src/modules/graphics/vulkan/StreamBuffer.cpp

@@ -96,7 +96,7 @@ ptrdiff_t StreamBuffer::getHandle() const
 	return (ptrdiff_t) buffer;
 }
 
-size_t getGPUReadOffset() const override
+size_t StreamBuffer::getGPUReadOffset() const
 {
 	return (frameIndex * bufferSize) + frameGPUReadOffset;
 }

src/modules/graphics/vulkan/StreamBuffer.h

@@ -47,6 +47,7 @@ public:
 
 	virtual void unloadVolatile() override;
 
+	size_t getGPUReadOffset() const override;
 	MapInfo map(size_t minsize) override;
 	size_t unmap(size_t usedSize) override;
 	void markUsed(size_t usedSize) override;