AndroidMkEntries() returns multiple AndroidMkEntries structs

AndroidMkEntries now returns multiple AndroidMkEntires so that a module
can emit multiple Make modules if needed.

Bug: 128708192
Test: m

Change-Id: I56b6f76d22943b80329951c5acb80a1b932441ad
diff --git a/sdk/sdk.go b/sdk/sdk.go
index c7e12b9..c25186a 100644
--- a/sdk/sdk.go
+++ b/sdk/sdk.go
@@ -163,12 +163,12 @@
 	}
 }
 
-func (s *sdk) AndroidMkEntries() android.AndroidMkEntries {
+func (s *sdk) AndroidMkEntries() []android.AndroidMkEntries {
 	if !s.snapshotFile.Valid() {
-		return android.AndroidMkEntries{}
+		return []android.AndroidMkEntries{}
 	}
 
-	return android.AndroidMkEntries{
+	return []android.AndroidMkEntries{android.AndroidMkEntries{
 		Class:      "FAKE",
 		OutputFile: s.snapshotFile,
 		DistFile:   s.snapshotFile,
@@ -180,7 +180,7 @@
 				fmt.Fprintln(w, s.Name()+":", s.snapshotFile.String())
 			},
 		},
-	}
+	}}
 }
 
 // RegisterPreDepsMutators registers pre-deps mutators to support modules implementing SdkAware