imx-vpuwrap: bump to version 1.0.68

Changelog:
- Coverity fixes for checkign return values, unused values, null checking
- H.263 encoder invalid frame rate

This patch is based on the Yocto equivalent:
https://github.com/Freescale/meta-freescale/commit/fd160ae9

Implicitly tested through gstreamer as the 0.10 plugin relies on it:
 # gst-launch-0.10 playbin uri=file:///root/tears_of_steel_1080p.webm



Signed-off-by: Gary Bisson <gary.bisson@boundarydevices.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>