If the buffer doesn't contain enough bytes when reading a stream,
fail rather than continuing on with initialized data. Caught by
Chromium fuzzeras (crbug.com/1065731).
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 5b967f56)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>