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/cc/snapshot_utils.go b/cc/snapshot_utils.go
index 8f48f86..73388ce 100644
--- a/cc/snapshot_utils.go
+++ b/cc/snapshot_utils.go
@@ -117,6 +117,17 @@
 	return outPath
 }
 
+func combineNotices(ctx android.SingletonContext, paths android.Paths, out string) android.OutputPath {
+	outPath := android.PathForOutput(ctx, out)
+	ctx.Build(pctx, android.BuildParams{
+		Rule:        android.Cat,
+		Inputs:      paths,
+		Output:      outPath,
+		Description: "combine notices for " + out,
+	})
+	return outPath
+}
+
 func writeStringToFile(ctx android.SingletonContext, content, out string) android.OutputPath {
 	outPath := android.PathForOutput(ctx, out)
 	ctx.Build(pctx, android.BuildParams{