Delete Hashable, pull up its members to Any

Extensions on nullable types remain in Library.kt

 #KT-1741 Obsolete
 #KT-2805 Obsolete
 #KT-1365 Fixed
 #KT-4517 In Progress

compiler/testData/codegen/box/fieldRename/genericPropertyWithItself.kt

@@ -1,7 +1,7 @@
 public class MPair<out A> (
         public val first: A
 ) {
-    fun equals(o: Any?): Boolean {
+    override fun equals(o: Any?): Boolean {
         val t = o as MPair<*>
         return first == t.first
     }