KT-43045 mangle function name for fake override with default impl

compiler/testData/codegen/box/inlineClasses/defaultInterfaceMethodsInInlineClass.kt

@@ -0,0 +1,13 @@
+interface IFoo<T> {
+    fun foo(x: T): String = "O"
+    fun T.bar(): String = "K"
+}
+
+inline class L(val x: Long) : IFoo<L>
+
+fun box(): String {
+    val z = L(0L)
+    return with(z) {
+        foo(z) + z.bar()
+    }
+}