Prepend default to allow overriding in the bp file.

Bug: 143948100
Bug: 151303681
Test: m nothing
Change-Id: Iefcf4fbe9d2971ce267242185165f0c38f68db30
diff --git a/sdk/sdk.go b/sdk/sdk.go
index c268505..3e76008 100644
--- a/sdk/sdk.go
+++ b/sdk/sdk.go
@@ -218,7 +218,7 @@
 			Compile_multilib *string
 		}
 		p := &props{Compile_multilib: proptools.StringPtr("both")}
-		ctx.AppendProperties(p)
+		ctx.PrependProperties(p)
 	})
 	return s
 }