Fix NPE on equals/hashCode of local function references

Anonymous classes for local function references implement their
getOwner() as "return null" currently (KT-14291). To avoid NPE in this
case, we now consider two local functions the same if their name and
signature are equal. This is incorrect in general, but unlikely to cause
major problems and is going to be fixed by KT-14291 eventually anyway

 #KT-17055

compiler/testData/codegen/box/callableReference/function/local/equalsHashCode.kt

@@ -0,0 +1,13 @@
+// IGNORE_BACKEND: JS, NATIVE
+
+fun box(): String {
+    fun bar() {}
+    fun baz() {}
+
+    if (!::bar.equals(::bar)) return "Fail 1"
+    if (::bar.hashCode() != ::bar.hashCode()) return "Fail 2"
+
+    if (::bar == ::baz) return "Fail 3"
+
+    return "OK"
+}