Workaround for the grcc failure

See https://github.com/ptrkrysik/gr-gsm/pull/378#issuecomment-379587145

Traceback (most recent call last):
  File "/usr/bin/grcc", line 29, in <module>
    from gnuradio import gr
  File "/usr/lib/python2.7/dist-packages/gnuradio/gr/__init__.py", line 41, in <module>
    from runtime_swig import *
  File "/usr/lib/python2.7/dist-packages/gnuradio/gr/runtime_swig.py", line 17, in <module>
    _runtime_swig = swig_import_helper()
  File "/usr/lib/python2.7/dist-packages/gnuradio/gr/runtime_swig.py", line 16, in swig_import_helper
    return importlib.import_module('_runtime_swig')
  File "/usr/lib/python2.7/importlib/__init__.py", line 37, in import_module
    __import__(name)
ImportError: No module named _runtime_swig
diff --git a/tests/dockerfiles/Kali.docker b/tests/dockerfiles/Kali.docker
index c844540..99b1cac 100644
--- a/tests/dockerfiles/Kali.docker
+++ b/tests/dockerfiles/Kali.docker
@@ -26,6 +26,9 @@
     # The parallel build sometimes fails when the .grc_gnuradio
     # and .gnuradio directories do not exist
     mkdir $HOME/.grc_gnuradio/ $HOME/.gnuradio/ && \
+    # Workaround for the grcc failure
+    # https://github.com/ptrkrysik/gr-gsm/pull/378#issuecomment-379587145
+    ln -sf /usr/lib/x86_64-linux-gnu/libvolk.so.1.3.1 /usr/lib/x86_64-linux-gnu/libvolk.so.1.3 && \
     make -j $(nproc) && \
     make install && \
     ldconfig && \