skip Imagine test on HHVM

tests/unit/extensions/imagine/ImageImagickTest.php

@@ -15,6 +15,8 @@ class ImageImagickTest extends AbstractImageTest
     {
         if (!class_exists('Imagick')) {
             $this->markTestSkipped('Skipping ImageImagickTest, Imagick is not installed');
+        } elseif (defined('HHVM_VERSION')) {
+            $this->markTestSkipped('Imagine does not seem to support HHVM right now.');
         } else {
             Image::setImagine(null);
             Image::$driver = Image::DRIVER_IMAGICK;