da5b6351e2
Test-add for the jlong return-type variant — same shape as 1.18's jint test but exercising `#jni_call(s64)(env, target, "currentTimeMillis", "()J")`. Today the non-void switch falls through to `LLVMGetUndef`; the IR snapshot captures the placeholder. The next commit adds the `.s64 => Jni.CallLongMethod` arm. The snapshot will update to show the full dispatch through vtable slot 52, reusing the 1.17 slot interning machinery.