Fix oggenc crash on raw file close, channel integer overflow, and
division by zero.

PR: 202941
Submitted by: junovitch
Obtained from: https://trac.xiph.org/changeset/19117
Obtained from: Fedora vorbis-tools Git (commit 63a1a62d)
Security: CVE-2014-9638
Security: CVE-2014-9639
Security: a35f415d-572a-11e5-b0a4-f8b156b6dcc8
MFH: 2015Q3