The State destructor was trying to unref a Program that had already
been deleted. Fix this by unbinding resources from State before we
exit the test.

BUG=554520

Change-Id: I2215b1e5d27a34a649572c8f81e96dfeef7e983e
Reviewed-on: https://chromium-review.googlesource.com/312977
Tryjob-Request: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>