Passing nullptr data to BufferImage would assert anyway.

I can't think of any valid use case, so no problem when these are
producing deprecated warnings.

src/Magnum/BufferImage.h

@@ -85,7 +85,6 @@ template<UnsignedInt dimensions> class BufferImage {
         /* To avoid decay of sized arrays and nullptr to const void* and
            unwanted use of deprecated function */
         template<class T, std::size_t dataSize> explicit BufferImage(PixelFormat format, PixelType type, const VectorTypeFor<dimensions, Int>& size, const T(&data)[dataSize], BufferUsage usage): BufferImage{{}, format, type, size, Containers::ArrayView<const void>{data}, usage} {}
-        explicit BufferImage(PixelFormat format, PixelType type, const VectorTypeFor<dimensions, Int>& size, std::nullptr_t, BufferUsage usage): BufferImage{{}, format, type, size, Containers::ArrayView<const void>{nullptr}, usage} {}
         #endif
         #endif
 
@@ -194,9 +193,6 @@ template<UnsignedInt dimensions> class BufferImage {
         template<class T, std::size_t dataSize> void setData(PixelFormat format, PixelType type, const VectorTypeFor<dimensions, Int>& size, const T(&data)[dataSize], BufferUsage usage) {
             setData({}, format, type, size, Containers::ArrayView<const void>{data}, usage);
         }
-        void setData(PixelFormat format, PixelType type, const VectorTypeFor<dimensions, Int>& size, std::nullptr_t, BufferUsage usage) {
-            setData({}, format, type, size, Containers::ArrayView<const void>{nullptr}, usage);
-        }
         #endif
         #endif