tests: define GST_CHECK_TEST_ENVIRONMENT_BEACON
tests: define GST_CHECK_TEST_ENVIRONMENT_BEACON

Make sure the test environment is set up.

https://bugzilla.gnome.org//show_bug.cgi?id=747624

Kurento/gst-plugins-ugly,GrokImageCompression/gst-plugins-ugly,GrokImageCompression/gst-plugins-ugly,StreamUtils/gst-plugins-ugly,Kurento/gst-plugins-ugly,shelsonjava/gst-plugins-ugly,StreamUtils/gst-plugins-ugly,GStreamer/gst-plugins-ugly,shelsonjava/gst-plugins-ugly,GrokImageCompression/gst-plugins-ugly,GStreamer/gst-plugins-ugly,Kurento/gst-plugins-ugly,shelsonjava/gst-plugins-ugly,GStreamer/gst-plugins-ugly,StreamUtils/gst-plugins-ugly