libvpx

Reduce the amount of extension in src frames

The commit changes the border pixel extension from 160 pixel each side
to what is necessary in arnr filter or motion estimation portion, i.e.
16 pixel on top and left side. For right or bottom side, the extension
is changed to either round up image size to multiple of 64 or at least
16 pixels.

Change-Id: Ic05e19b94368c1ab4df568723aae5734e6c3d2c5