Fix the parallel build.

- Override the GR_UNIQUE_TARGET function to not append a hash to the
  target name.
- Add explicit dependency between pygen_apps and _grgsm_swig
  The _grgs_swig needs to be built first because grcc evaluates and
  verify all imports
- Test the parallel build in the docker containers as well
diff --git a/tests/dockerfiles/Kali.docker b/tests/dockerfiles/Kali.docker
index 3cb3257..c844540 100644
--- a/tests/dockerfiles/Kali.docker
+++ b/tests/dockerfiles/Kali.docker
@@ -23,7 +23,10 @@
 RUN mkdir /src/build
 WORKDIR /src/build
 RUN cmake .. && \
-    make && \
+    # The parallel build sometimes fails when the .grc_gnuradio
+    # and .gnuradio directories do not exist
+    mkdir $HOME/.grc_gnuradio/ $HOME/.gnuradio/ && \
+    make -j $(nproc) && \
     make install && \
     ldconfig && \
     make test