Try to fix travis build

Author: oledid

.travis.yml

@@ -1,14 +1,15 @@
 language: node_js
 node_js:
-- '6'
+- '12'
 env:
-  - CXX=g++-4.8
+  - CXX=g++-4.9
+  - CXX=clang++
 addons:
   apt:
     sources:
       - ubuntu-toolchain-r-test
     packages:
-      - g++-4.8
+      - g++-4.9
 deploy:
   - provider: npm
     email: [email protected]