Do not generate @NotNull annotations on void- or primitive-returning methods

#KT-4834 Fixed
  #KT-5255 Fixed

compiler/testData/asJava/lightClasses/nullabilityAnnotations/OverrideAnyWithUnit.java

@@ -0,0 +1,5 @@
+public final class C implements kotlin.jvm.internal.KObject, Base {
+    public void foo() { /* compiled code */ }
+
+    public C() { /* compiled code */ }
+}