rather than symlink the webm/vpx terms, use the same header as libvpx to reference in-tree files based on the discussion in: https://codereview.chromium.org/12771026/ Change-Id: Ia3067ecddefaa7ee01550136e00f7b3f086d4af4
relocates the static functions from metadata.h and adds MetadataCopy() to the interface Change-Id: I28bfa9233d3dd70dddf6b561fe0bf4be378db1ec