use travis php image

dist: trusty

sudo: required

language: cpp

language: php

addons:

    apt:

        sources:

            - sourceline: 'ppa:ondrej/php'

            - sourceline: 'ppa:ubuntu-toolchain-r/test'

        packages:

            - php7.1-dev

            - autoconf

            - build-essential

            - gcc-5

            - g++-5

php:

  - '7.1'

before_install:

    - export CC=gcc-5

    - export CXX=g++-5

script:

    - dpkg -l | grep php

    - ls /usr/bin | grep php

    - phpize7.1

    - phpize

    - ./configure --enable-bencode

    - make -j$(nproc)

    - make test