Move cpplint invocation into a separate job

Author: vitalybuka

.travis.yml

@@ -43,14 +43,19 @@ matrix:
     - env: BUILD_TYPE=Debug CC_COMPILER=gcc-${GCC_VERSION} CXX_COMPILER=g++-${GCC_VERSION}
       addons: *gcc
 
+    - env:
+      install:
+      before_script:
+      script:
+        - travis_retry wget --quiet -O - https://raw.githubusercontent.com/cpplint/cpplint/master/cpplint.py | python - --recursive src examples
+
 install:
   - mkdir -p deps && cd deps
   - travis_retry wget --no-check-certificate --quiet -O - https://cmake.org/files/v3.12/cmake-3.12.3-Linux-x86_64.tar.gz | tar --strip-components=1 -xz
   - export PATH=${TRAVIS_BUILD_DIR}/deps/bin:${PATH}
   - cd -
 
 before_script:
-  - travis_retry wget --quiet -O - https://raw.githubusercontent.com/cpplint/cpplint/master/cpplint.py | python - --recursive src examples
   - mkdir -p build && cd build
   - rm -rf *
   - cmake .. -GNinja -DLIB_PROTO_MUTATOR_WITH_ASAN=ON -DLIB_PROTO_MUTATOR_DOWNLOAD_PROTOBUF=ON -DCMAKE_C_COMPILER=${CC_COMPILER} -DCMAKE_CXX_COMPILER=${CXX_COMPILER} -DCMAKE_BUILD_TYPE=${BUILD_TYPE} -DCMAKE_INSTALL_PREFIX=/usr
@@ -59,4 +64,4 @@ script:
   - export ASAN_OPTIONS=detect_leaks=0
   - ninja
   - ninja check
-  - DESTDIR="/tmp/testing/" ninja install
+  - DESTDIR="/tmp/testing/" ninja install