tests: use NullSignature

Change-Id: Icb8ff95905cfa2ba9d9a493d7a60b30a61a8d671
diff --git a/.jenkins.d/00-deps.sh b/.jenkins.d/00-deps.sh
index 05ad5d1..67ac9ae 100755
--- a/.jenkins.d/00-deps.sh
+++ b/.jenkins.d/00-deps.sh
@@ -25,7 +25,7 @@
 
 elif has Ubuntu $NODE_LABELS; then
     sudo apt-get -qq update
-    sudo apt-get -qy install g++ pkg-config python3-minimal \
+    sudo apt-get -qy install build-essential pkg-config python3-minimal \
                              libboost-all-dev libssl-dev libsqlite3-dev \
                              libpcap-dev libsystemd-dev