Add faster implementation of descale

Dockerfile

@@ -44,6 +44,16 @@ RUN cd /tmp \
     && cd .. \
     && rm -rf VapourSynth-DCTFilter
 
+# Double speed for getnative
+RUN cd /tmp/ \
+    && git clone --depth=1 https://github.com/BluBb-mADe/vapoursynth-descale \
+    && cd vapoursynth-descale \
+    && g++ -std=c++17 -shared -fPIC -O2 descale.cpp -o libdescale.so \
+    && cp descale.py /usr/lib/python3/dist-packages/ \
+    && cp libdescale.so /usr/lib/x86_64-linux-gnu/vapoursynth/ \
+    && cd .. \
+    && rm -rf vapoursynth-descale
+
 RUN pip3 --no-cache-dir install \
         matplotlib \
         tqdm \