Ignore fake overrides when generating stub methods for MutableCollections

Because it's redundant as we go through all mutable collection hierarchy anyway
It wasn't a problem because for fake override just `generatedBridges` is being called
and there were no special bridges for such methods.

compiler/backend/src/org/jetbrains/kotlin/codegen/CollectionStubMethodGenerator.kt

@@ -199,7 +199,7 @@ class CollectionStubMethodGenerator(
         OverrideResolver.generateOverridesInAClass(klass, listOf(), object : OverridingUtil.DescriptorSink {
             override fun addFakeOverride(fakeOverride: CallableMemberDescriptor) {
                 if (fakeOverride !is FunctionDescriptor) return
-                if (fakeOverride.findOverriddenFromDirectSuperClass(mutableCollectionClass) != null) {
+                if (fakeOverride.findOverriddenFromDirectSuperClass(mutableCollectionClass)?.kind == DECLARATION) {
                     result.add(fakeOverride)
                 }
             }