Compile Vips 8.5.8 on Travis CI

.travis.yml

dist: trusty

before_install:
  - chmod +x travis_compile_vips.sh
  - ./travis_compile_vips.sh

cache:
  directories:
    - vips-8.5.8

travis_compile_vips.sh

#!/bin/sh
set -ex

if [ -d "vips-8.5.8"]; then
  cd vips-8.5.8/
  sudo make install;
else
  curl -L https://github.com/jcupitt/libvips/releases/download/v8.5.8/vips-8.5.8.tar.gz | tar xz;
  cd vips-8.5.8;
  sudo dpkg --configure -a;
  sudo sh -c ' echo "/usr/local/lib/" >> /etc/ld.so.conf.d/local.conf;'
  ./configure;
  make;
  sudo make install;
fi