Make opusfile_example fwrites all-or-nothing.
Make opusfile_example fwrites all-or-nothing.

This makes it more likely the WAV file header matches the amount of
 data actually written if we run out of space.
This is easier than making the accounting better.

gcp/opusfile,xiph/opusfile,SmartWalkieOrg/opusfile,youfearm3/opusfile,xiph/opusfile,xiph/opusfile,youfearm3/opusfile,SmartWalkieOrg/opusfile,gcp/opusfile,SmartWalkieOrg/opusfile,gcp/opusfile