mjpeg: Try to handle misformed streams.
mjpeg: Try to handle misformed streams.

Cameras such as D-Link's DCS-932L don't provide the first video
boundary.

xkfz007/vlc,xkfz007/vlc,jomanmuk/vlc-2.2,vlc-mirror/vlc,vlc-mirror/vlc,xkfz007/vlc,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.1,jomanmuk/vlc-2.1,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,shyamalschandra/vlc,shyamalschandra/vlc,vlc-mirror/vlc-2.1,vlc-mirror/vlc,jomanmuk/vlc-2.1,vlc-mirror/vlc-2.1,krichter722/vlc,vlc-mirror/vlc-2.1,krichter722/vlc,shyamalschandra/vlc,xkfz007/vlc,shyamalschandra/vlc,xkfz007/vlc,jomanmuk/vlc-2.1,krichter722/vlc,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.1,vlc-mirror/vlc,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.1,krichter722/vlc,shyamalschandra/vlc,jomanmuk/vlc-2.2,vlc-mirror/vlc,shyamalschandra/vlc,vlc-mirror/vlc,krichter722/vlc,vlc-mirror/vlc-2.1,xkfz007/vlc,jomanmuk/vlc-2.1,vlc-mirror/vlc-2.1,xkfz007/vlc,krichter722/vlc,krichter722/vlc,shyamalschandra/vlc,vlc-mirror/vlc