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
CloseHandle returns non-zero on success so earlier versions would leave
'ok' with a misleading value, though the return itself was correct.
Change-Id: I21b74a59d90f7bf1b484a55f3960962e933f577b