isula-build: fix goroutine leaks because status channel not closed

When parse dockerfile failed, status channel has not been closed,
which causes goroutine leaks.
So cleanup defer function which includes channel close should be put
in the beginning of Build to avoid parse dockerfile or newstagebuilder
returns error.
Signed-off-by: Nxiadanni <xiadanni1@huawei.com>

builder/dockerfile/builder.go

@@ -408,6 +408,11 @@ func (b *Builder) Build() (string, error) {
 		imageID      string
 	)
 
+	// 6. defer cleanup
+	defer func() {
+		b.cleanup()
+	}()
+
 	// 1. parseFiles
 	if err = b.parseFiles(); err != nil {
 		return "", err
@@ -418,11 +423,6 @@ func (b *Builder) Build() (string, error) {
 		return "", err
 	}
 
-	// 6. defer cleanup
-	defer func() {
-		b.cleanup()
-	}()
-
 	// 3. loop StageBuilders for building
 	for _, stage := range b.stageBuilders {
 		stageTimer := b.cliLog.StartTimer(fmt.Sprintf("Stage %d", stage.position))