ci: add clang 12 (dev snapshot) to Travis CI build matrix

Change-Id: I45266be56d700434b84aab5f5954828f5df1b598
diff --git a/.jenkins.d/00-deps.sh b/.jenkins.d/00-deps.sh
index 8d98130..3b5228f 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