bintrans: Error out if writing to the output failed.

• Cover all code paths.
• When decoding, check all output files, not just the last one.
• A simple ferror() check is not enough as an error may later occur while flushing whatever remains in the output buffer.

MFC after: 1 week
Sponsored by: Klara, Inc.
Reviewed by: allanjude
Differential Revision: https://reviews.freebsd.org/D43532