Skip resource verification on intermediate android libraries

The use case for this is kythe builds, which still use the legacy
resource processor. https://r.android.com/3207856 special-cased kythe
builds to use the legacy resource processor and retain R.srcjar xrefs.
This unfortunately broke xrefs for android apps that have android
library dependencies with unresolved resource references.

With this CL, the resource verification will be done only on the
top-level app for both ResourceProcessorBusyBox and the legacy
processor builds.

Test: XREF_CORPUS=blah m Traceur-res # builds now
Test: presubmits
Bug: 354854007
Change-Id: Ibc0eaa220a2eb233078c325318ef3bece243f375
diff --git a/java/aar.go b/java/aar.go
index 7d73b03..41cc24a 100644
--- a/java/aar.go
+++ b/java/aar.go
@@ -483,9 +483,9 @@
 	}
 
 	linkFlags = append(linkFlags, "--no-static-lib-packages")
-	if a.isLibrary && a.useResourceProcessorBusyBox(ctx) {
-		// When building an android_library using ResourceProcessorBusyBox pass --merge-only to skip resource
-		// references validation until the final app link step when all static libraries are present.
+	if a.isLibrary {
+		// Pass --merge-only to skip resource references validation until the final
+		// app link step when when all static libraries are present.
 		linkFlags = append(linkFlags, "--merge-only")
 	}