fix: validate bpf example

web3.js/.travis.yml

@@ -14,11 +14,20 @@ cache:
 notifications:
   email: false
 
+before_install:
+  - wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
+  - sudo apt-add-repository "deb http://apt.llvm.org/trusty/ llvm-toolchain-trusty-7 main"
+  - sudo apt-add-repository "deb http://ppa.launchpad.net/ubuntu-toolchain-r/test/ubuntu trusty main"
+  - sudo apt-get update
+  - sudo apt-get install -y clang-7 --allow-unauthenticated
+  - clang-7 --version
+
 script:
   - npm run doc
   - npm run flow
   - npm run lint
   - npm run codecov
+  - make -C examples/bpf-c-noop/
   - npm run localnet:update
   - npm run localnet:up
   - npm run examples