Fixed FLV::Tag.offset() return value for non-H264 packets.
Fixed FLV::Tag.offset() return value for non-H264 packets.

DDVTECH/mistserver,rbouqueau/libdtsc_xp,rbouqueau/libdtsc_xp,DDVTECH/mistserver,rbouqueau/libdtsc_xp,DDVTECH/mistserver,DDVTECH/mistserver,DDVTECH/mistserver