make ALIGN_xxx naming consistent

(potentially for future factorization between enc/ and dec/)

Change-Id: Ibf6670e21433a6a6a7202dcbe76f7efc8493b8cf
factorize BPS definition in dsp.h and add VP8Copy16x8

Change-Id: Id73a1e968c96455808755df4d131d74e3e2e135d
cosmetics: add some missing != NULL comparisons

Change-Id: I55f8da527e5e8ee4b49c7e7aa0d61ea4a6c80904
Merge changes I55f8da52,Id73a1e96

* changes:
  cosmetics: add some missing != NULL comparisons
  factorize BPS definition in dsp.h and add VP8Copy16x8