Make uses_libs and optional_uses_libs configurable

Requested for the mk2bp conversion.

Fixes: 373772769
Test: m nothing --no-skip-soong-tests
Change-Id: I9a36e73f20c73e25b555fb3f0a074b30a548ae50
diff --git a/java/base.go b/java/base.go
index a9399cb..f6764b6 100644
--- a/java/base.go
+++ b/java/base.go
@@ -862,7 +862,7 @@
 					// explicitly listed in the optional_uses_libs property.
 					tag := usesLibReqTag
 					if android.InList(*lib, dexpreopt.OptionalCompatUsesLibs) ||
-						android.InList(*lib, j.usesLibrary.usesLibraryProperties.Optional_uses_libs) {
+						android.InList(*lib, j.usesLibrary.usesLibraryProperties.Optional_uses_libs.GetOrDefault(ctx, nil)) {
 						tag = usesLibOptTag
 					}
 					ctx.AddVariationDependencies(nil, tag, *lib)