[Libva] [PATCH Intel-VA] Add if statement checking for obj_context that possible assign to NULL value.

[Lim, Siew Hoon]

> 
> Hi Lim,
> 
> May I suggest that one tweaks the commit message a bit. Something like
> "Avoid NULL ptr deref in i965_decoder_wrapper_picture()" or "Error out
> when obj_context is NULL" seems much better imho.

Hi Emil,
Sure, thanks for the feedback. I will modify the commit message.
...siewhoon

> 
> -Emil