Speed up hhvm unit tests - disable jit

Turn off the hhvm JIT to speed up the hhvm unit tests.

Source for why the JIT is bad for unit testing: facebook/hhvm#6979

.travis.yml

@@ -43,6 +43,8 @@ install:
   - wget -O ~/.phpenv/versions/hhvm/bin/phpunit https://phar.phpunit.de/phpunit.phar
   - chmod 755 ~/.phpenv/versions/hhvm/bin/phpunit
 before_script:
+  # Disable the HHVM JIT for faster Unit Testing
+  - if [[ $TRAVIS_PHP_VERSION = hhv* ]]; then echo 'hhvm.jit = 0' >> /etc/hhvm/php.ini; fi
   - test -z "$DISABLE_FUNCTIONS" || echo "disable_functions=$DISABLE_FUNCTIONS" >> ~/.phpenv/versions/$(phpenv version-name)/etc/conf.d/travis.ini
   - cp _test/mysql.conf.php.dist _test/mysql.conf.php
   - cp _test/pgsql.conf.php.dist _test/pgsql.conf.php