Fix tinyxml2 dependency

Change-Id: I0a7a317e0e91e3b50e7b84d0c8d6e0fc6f08e7d4
Signed-off-by: Matt Spinler <spinler@us.ibm.com>
diff --git a/build-unit-test-docker.sh b/build-unit-test-docker.sh
index 22e54e6..316f1ba 100755
--- a/build-unit-test-docker.sh
+++ b/build-unit-test-docker.sh
@@ -118,7 +118,7 @@
     libpam0g-dev \
     xxd \
     wget \
-    tinyxml2
+    libtinyxml2-6
 
 RUN pip install inflection
 RUN pip install pycodestyle