Test against the current hhvm version

This provides the current HHVM version (3.15.3 as of this PR) and will track with each release (i.e. will be 3.16 when 3.16 is released.

If testing against HHVM LST versions is desired follow this guide. https://docs.travis-ci.com/user/languages/php#HHVM-versions

Should be able to change to container based Trusty after Q1-17 https://blog.travis-ci.com/2016-11-08-trusty-container-public-beta/

.travis.yml

@@ -7,11 +7,27 @@ php:
   - "5.5"
   - "5.4"
   - "5.3"
-  - "hhvm"
+
 env:
   - DISABLE_FUNCTIONS=
   - DISABLE_FUNCTIONS="gzopen"
 matrix:
+  fast_finish: true
+  include:
+    - php: hhvm
+      sudo: true
+      dist: trusty
+      group: edge # until the next update
+      addons:
+        apt:
+          packages:
+            - mysql-server-5.6
+            - mysql-client-core-5.6
+            - mysql-client-5.6
+      services:
+        - mysql
+        - postgresql
+      env: DISABLE_FUNCTIONS=
   allow_failures:
     - php: "hhvm"
   exclude:
@@ -23,9 +39,6 @@ notifications:
         - "chat.freenode.net#dokuwiki"
     on_success: change
     on_failure: change
-services:
-  - "mysql"
-  - "postgresql"
 install:
   - wget -O ~/.phpenv/versions/hhvm/bin/phpunit https://phar.phpunit.de/phpunit.phar
   - chmod 755 ~/.phpenv/versions/hhvm/bin/phpunit