loop_restoration: Prevent some wild memory access
loop_restoration: Prevent some wild memory access

On recode frames the encoder will attempt to serialize the bitstream
before choosing loop filter parameters to get a rough size estimate.
This can result in wild reads in encode restoration if leftover values
from the previous frame aren't available.

Even with a realloc instead of free-ing and reallocing all the data,
wild reads are possible on frame size changes.

Change-Id: I9956d9e11c6ed61999563436051c2fe469718538

smarter/aom,luctrudeau/aom,smarter/aom,luctrudeau/aom,luctrudeau/aom,luctrudeau/aom,smarter/aom,smarter/aom,luctrudeau/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,smarter/aom,luctrudeau/aom,GrokImageCompression/aom,smarter/aom,GrokImageCompression/aom