Also install the llvm package, tsk tsk

.travis.yml

@@ -34,7 +34,7 @@ before_install:
       sudo apt-add-repository -y
         'deb http://apt.llvm.org/trusty/ llvm-toolchain-trusty-4.0 main';
       sudo apt-get update;
-      sudo apt-get install -y clang-4.0;
+      sudo apt-get install -y clang-4.0 llvm-4.0;
       export CC="clang-4.0";
       export CONFIGURE_ARGS="--enable-asan --enable-ubsan";
       export ASAN_OPTIONS="detect_odr_violation=0,detect_leaks=0,abort_on_error=1";