Check rangebits to avoid a possible crash.
Fixes issue 2548 (and Chrome issue 68115 and unknown CERT issues).

Originally committed as revision 26365 to svn://svn.ffmpeg.org/ffmpeg/trunk
(cherry picked from commit 13184036a6b1b1d4b61c91118c0896e9ad4634c3)

Addresses: CVE-2011-0480

Conflicts:

	libavcodec/vorbis_dec.c
1 file changed