The WienerInfo struct requires a 16-byte alignment on x86,
since it contains filter coefficients which are loaded using
SSE aligned load instructions. But on 32-bit x86, the default
alignment of aom_malloc/aom_realloc is only 8 bytes, leading
to occasional segfaults.

To fix this, rather than using aom_realloc to resize WienerInfo
structures, we always free and re-allocate them using aom_memalign

BUG=aomedia:345

Change-Id: Ib1b2a42d4a2fa215dcc81ea481c51271ab068a37