libvpx

Merge branch 'indianrunnerduck'

* indianrunnerduck:
  Update CHANGELOG for v1.4.0 (Indian Runner Duck) release
  vp9: fix high-bitdepth NEON build
  Fix use of scaling in joint motion search
  Prepare Release Candidate for libvpx v1.4.0
  vp8cx.h: vpx/vpx_encoder.h -> ./vpx_encoder.h

Change-Id: Ib2eee50f02e12623aae478871cb9150604bb2ac2