Add unit tests for class loader context.

Test: lunch aosp_cf_x86_phone-userdebug && m
Bug: 132357300
Change-Id: I96a1e6cef86652e429b1678a655fc0b02f40d00c
diff --git a/dexpreopt/dexpreopt.go b/dexpreopt/dexpreopt.go
index 51d1157..a07f1fa 100644
--- a/dexpreopt/dexpreopt.go
+++ b/dexpreopt/dexpreopt.go
@@ -81,7 +81,9 @@
 	}
 
 	if !dexpreoptDisabled(ctx, global, module) {
-		if clc := genClassLoaderContext(ctx, global, module); clc != nil {
+		if clc, err := genClassLoaderContext(ctx, global, module); err != nil {
+			android.ReportPathErrorf(ctx, err.Error())
+		} else if clc != nil {
 			appImage := (generateProfile || module.ForceCreateAppImage || global.DefaultAppImages) &&
 				!module.NoCreateAppImage