Add missing imports.

avformat/context.go

@@ -11,6 +11,7 @@ import (
 	"unsafe"
 
 	"github.com/giorgisio/goav/avcodec"
+	"github.com/giorgisio/goav/avutil"
 )
 
 const (

avformat/context_struct.go

@@ -9,6 +9,8 @@ import "C"
 import (
 	"reflect"
 	"unsafe"
+
+	"github.com/giorgisio/goav/avutil"
 )
 
 func (ctxt *Context) Chapters() **AvChapter {

avformat/stream_struct.go

@@ -10,6 +10,7 @@ import (
 	"unsafe"
 
 	"github.com/giorgisio/goav/avcodec"
+	"github.com/giorgisio/goav/avutil"
 )
 
 func (avs *Stream) CodecParameters() *avcodec.AvCodecParameters {