avoid warnings on super abstract methods that they try to assign weaker access (IDEA-67584)

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/genericsHighlighting/IDEA67584.java

@@ -0,0 +1,11 @@
+abstract class A
+{
+    abstract void foo();
+}
+
+interface B
+{
+    abstract void foo();
+}
+
+abstract class C extends A implements B { }