fix HHVM dep
fix HHVM dep

rs-makino/buildpack-test,jayelkaake/heroku-buildpack-magento,alzheic/heroku-buildpack-aop,rikur/heroku-buildpack-php,emeth-/heroku-buildpack-php,0ppy/sample-buildpack,jopereyral/heroku-buildpack-php,rs-makino/buildpack-test,dzuelke/heroku-buildpack-php,emeth-/heroku-buildpack-php,puteulanus/heroku-buildpack-php,martijngastkemper/heroku-buildpack-php,thecsea/heroku-buildpack-php-with-ioncube,emeth-/heroku-buildpack-php,rs-makino/buildpack-test,heroku/heroku-buildpack-php,dzuelke/heroku-buildpack-php,rs-makino/buildpack-test,rs-makino/buildpack-test,heroku/heroku-buildpack-php,rikur/heroku-buildpack-php,jayelkaake/heroku-buildpack-magento,puteulanus/heroku-buildpack-php,thecsea/heroku-buildpack-php-with-ioncube,flant/heroku-buildpack-php,a2service/heroku-buildpack-php,createmultimedia/heroku-buildpack-php,jopereyral/heroku-buildpack-php,rikur/heroku-buildpack-php,a2service/heroku-buildpack-php,dzuelke/heroku-buildpack-php,rs-makino/buildpack-test,emeth-/heroku-buildpack-php,flant/heroku-buildpack-php,martijngastkemper/heroku-buildpack-php,rikur/heroku-buildpack-php,puteulanus/heroku-buildpack-php,heroku/heroku-buildpack-php,createmultimedia/heroku-buildpack-php,jopereyral/heroku-buildpack-php,alzheic/heroku-buildpack-aop,alzheic/heroku-buildpack-aop,flant/heroku-buildpack-php,0ppy/sample-buildpack,thecsea/heroku-buildpack-php-with-ioncube,jayelkaake/heroku-buildpack-magento,createmultimedia/heroku-buildpack-php,heroku/heroku-buildpack-php,a2service/heroku-buildpack-php,0ppy/sample-buildpack