VNDK APEX: skips VNDK-Ext

In legacy VNDK mode (DeviceVndkVesion=""), the check was missing. We
don't want VNDK-Ext in VNDK APEX in any case.

Bug: 191770320
Test: m nothing
Change-Id: I08f36a4c1696bf82d25d629841e172d2716a366d
diff --git a/cc/vndk.go b/cc/vndk.go
index dd1c3e1..0b40076 100644
--- a/cc/vndk.go
+++ b/cc/vndk.go
@@ -371,7 +371,7 @@
 			if mctx.ModuleName() == "libz" {
 				return false
 			}
-			return m.ImageVariation().Variation == android.CoreVariation && lib.shared() && m.IsVndkSp()
+			return m.ImageVariation().Variation == android.CoreVariation && lib.shared() && m.IsVndkSp() && !m.IsVndkExt()
 		}
 
 		useCoreVariant := m.VndkVersion() == mctx.DeviceConfig().PlatformVndkVersion() &&