apex_vndk uses vendor variants only

VNDK APEX is supposed to contain "vendor" variants of VNDK libraries.
This is different from normal APEXes which have "apex" variants.

Bug: 146758869
Test: build / flash / boot
Change-Id: I5e035678c337334092616b58d2e0e404788a6639
Exempt-From-Owner-Approval: Got ORV, but rebased with resolving merge conflicts.
diff --git a/apex/apex.go b/apex/apex.go
index d908cd3..08ee18a 100644
--- a/apex/apex.go
+++ b/apex/apex.go
@@ -333,7 +333,7 @@
 // Mark the direct and transitive dependencies of apex bundles so that they
 // can be built for the apex bundles.
 func apexDepsMutator(mctx android.BottomUpMutatorContext) {
-	if a, ok := mctx.Module().(*apexBundle); ok {
+	if a, ok := mctx.Module().(*apexBundle); ok && !a.vndkApex {
 		apexBundleName := mctx.ModuleName()
 		mctx.WalkDeps(func(child, parent android.Module) bool {
 			depName := mctx.OtherModuleName(child)
@@ -361,7 +361,7 @@
 func apexMutator(mctx android.BottomUpMutatorContext) {
 	if am, ok := mctx.Module().(android.ApexModule); ok && am.CanHaveApexVariants() {
 		am.CreateApexVariations(mctx)
-	} else if _, ok := mctx.Module().(*apexBundle); ok {
+	} else if a, ok := mctx.Module().(*apexBundle); ok && !a.vndkApex {
 		// apex bundle itself is mutated so that it and its modules have same
 		// apex variant.
 		apexBundleName := mctx.ModuleName()