Build VNDK with VNDK prebuilts without BOARD_VNDK_VERSION

Current VNDK prebuilts are disabled if BOARD_VNDK_VERSION is not set,
but VNDK prebuilts should be enabled even BOARD_VNDK_VERSION is not set
because VNDK APEXes should be available from VNDK deprecation. This
change removes some restrictions on VNDK prebuilts to enable those from
VNDK deprecation.

Bug: 316829758
Test: AOSP Cuttlefish build succeeded without BOARD_VNDK_VERSION
Change-Id: Id780811dab26f2125097c3efc5b2b4a59416b826
diff --git a/cc/vndk_prebuilt.go b/cc/vndk_prebuilt.go
index eb1790f..801e5f0 100644
--- a/cc/vndk_prebuilt.go
+++ b/cc/vndk_prebuilt.go
@@ -131,11 +131,14 @@
 
 func (p *vndkPrebuiltLibraryDecorator) link(ctx ModuleContext,
 	flags Flags, deps PathDeps, objs Objects) android.Path {
-	platformVndkApiLevel := android.ApiLevelOrPanic(ctx, ctx.DeviceConfig().PlatformVndkVersion())
-	if platformVndkApiLevel.LessThanOrEqualTo(android.ApiLevelOrPanic(ctx, p.Version())) {
-		// This prebuilt VNDK module is not required for the current build
-		ctx.Module().HideFromMake()
-		return nil
+	platformVndkVersion := ctx.DeviceConfig().PlatformVndkVersion()
+	if platformVndkVersion != "" {
+		platformVndkApiLevel := android.ApiLevelOrPanic(ctx, platformVndkVersion)
+		if platformVndkApiLevel.LessThanOrEqualTo(android.ApiLevelOrPanic(ctx, p.Version())) {
+			// This prebuilt VNDK module is not required for the current build
+			ctx.Module().HideFromMake()
+			return nil
+		}
 	}
 
 	if !p.MatchesWithDevice(ctx.DeviceConfig()) {
@@ -246,14 +249,6 @@
 		&prebuilt.properties,
 	)
 
-	android.AddLoadHook(module, func(ctx android.LoadHookContext) {
-		// empty BOARD_VNDK_VERSION implies that the device won't support
-		// system only OTA. In this case, VNDK snapshots aren't needed.
-		if ctx.DeviceConfig().VndkVersion() == "" {
-			ctx.Module().Disable()
-		}
-	})
-
 	return module
 }