Add packages for xmllint and XML::Simple Perl module

Signed-off-by: Zane Shelley <zshelle@us.ibm.com>
Change-Id: I4b95b6c1dea7baa9d903da45cb54adca921b0e30
diff --git a/build-unit-test-docker.sh b/build-unit-test-docker.sh
index e690d9a..4b6075f 100755
--- a/build-unit-test-docker.sh
+++ b/build-unit-test-docker.sh
@@ -263,7 +263,9 @@
     device-tree-compiler \
     cppcheck \
     libpciaccess-dev \
-    libmimetic-dev
+    libmimetic-dev \
+    libxml2-utils \
+    libxml-simple-perl
 
 RUN update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-10 1000 \
   --slave /usr/bin/g++ g++ /usr/bin/g++-10 \