libvpx

replace DECLARE_ALIGNED_ARRAY w/DECLARE_ALIGNED

this macro was used inconsistently and only differs in behavior from
DECLARE_ALIGNED when an alignment attribute is unavailable. this macro
is used with calls to assembly, while generic c-code doesn't rely on it,
so in a c-only build without an alignment attribute the code will
function as expected.

Change-Id: Ie9d06d4028c0de17c63b3a27e6c1b0491cc4ea79