Add dockerfile for building the ggsn-test from osmo-ttcn3c-hacks.git

ggsn-test/Dockerfile

@@ -0,0 +1,12 @@
+FROM	debian-stretch-titan
+
+RUN	git clone git://git.osmocom.org/osmo-ttcn3-hacks.git && \
+	mkdir /root/projects && (cd /root/projects && ln -sf / git) && \
+	cd osmo-ttcn3-hacks/ggsn_tests && \
+	./gen_links.sh && \
+	./regen_makefile.sh && \
+	make compile && \
+	make -j8
+
+CMD	cd osmo-ttcn3-hacks/ggsn_tests && \
+	ttcn3_start ./GGSN_Tests ./GGSN_Tests.cfg && ttcn3_logmerge *.log