Unless overridden include LICENSE files in notices.

As a second step to removing the go/android3p instructions to copy or
to link NOTICE to LICENSE, include LICENSE files in the notices, which
will allow deleting all of the copied/linked NOTICE files.

The change causes a few additions to the system image notice files.

Test: manually built and compared before and after notices
Change-Id: Ia7bc58e2eba7bed5e63934881b5298201a93bc3e
diff --git a/apex/builder.go b/apex/builder.go
index 88c7098..b9736d3 100644
--- a/apex/builder.go
+++ b/apex/builder.go
@@ -215,15 +215,15 @@
 	noticeFiles := []android.Path{}
 	for _, f := range a.filesInfo {
 		if f.module != nil {
-			notice := f.module.NoticeFile()
-			if notice.Valid() {
-				noticeFiles = append(noticeFiles, notice.Path())
+			notices := f.module.NoticeFiles()
+			if len(notices) > 0 {
+				noticeFiles = append(noticeFiles, notices...)
 			}
 		}
 	}
 	// append the notice file specified in the apex module itself
-	if a.NoticeFile().Valid() {
-		noticeFiles = append(noticeFiles, a.NoticeFile().Path())
+	if len(a.NoticeFiles()) > 0 {
+		noticeFiles = append(noticeFiles, a.NoticeFiles()...)
 	}
 
 	if len(noticeFiles) == 0 {