Prevent integer overflow when processing covr MPEG4 atoms

If the 'chunk_data_size' value is SIZE_MAX, an integer overflow will occur
and cause an undersized buffer to be allocated. The following processing
then overfills the resulting memory and creates a potentially exploitable
condition. Ensure that integer overflow does not occur.

(cherrypicked from commit 05ddc499)

Bug: 20923261
Change-Id: If09a02738759acdff8d95149bb9cb5f18a0a123e