audio/opusfile: Fix QA issues

> Checking for pkg-plist issues (check-plist)

> Parsing plist

> Checking for items in STAGEDIR missing from pkg-plist

Error: Orphaned: %%PORTDOCS%%%%DOCSDIR%%/COPYING

> Checking for items in pkg-plist which are not in STAGEDIR

> Error: Plist issues found.

http://package21.nyi.freebsd.org/data/114amd64-default-qat/566258/logs/errors/opusfile-0.12.log