Dockerfile: just use module location from apt (but make writable)

Dockerfile

@@ -14,9 +14,6 @@ ENV PYTHONIOENCODING utf8
 # so let XDG_DATA_HOME coincide with fixed system location
 # (can still be overridden by derived stages)
 ENV XDG_DATA_HOME /usr/local/share
-# allow using resmgr data location but still keep internal module location
-RUN mkdir -p $XDG_DATA_HOME/ocrd-resources
-RUN ln -rs /usr/share/tesseract-ocr/4.00/tessdata $XDG_DATA_HOME/ocrd-resources/ocrd-tesserocr-recognize
 
 WORKDIR /build-ocrd
 COPY setup.py .
@@ -32,6 +29,8 @@ RUN make deps-ubuntu && \
     && make deps install \
     && rm -rf /build-ocrd \
     && apt-get -y remove --auto-remove g++ libtesseract-dev make
+# PPA tessdata prefix (= ocrd_tesserocr moduledir) is owned by root
+RUN sudo chmod go+w `dpkg-query -L tesseract-ocr-eng | sed -n s,/eng.traineddata,,p`
 RUN ocrd resmgr download ocrd-tesserocr-recognize Fraktur.traineddata
 RUN ocrd resmgr download ocrd-tesserocr-recognize deu.traineddata