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
     }

compiler/testData/codegen/box/functions/defaultargs2.kt

@@ -4,7 +4,7 @@ class T4(
   val c3: Boolean,
   val c4: String
 ) {
-  fun equals(o: Any?): Boolean {
+  override fun equals(o: Any?): Boolean {
     if (o !is T4) return false;
     return c1 == o.c1 &&
       c2 == o.c2 &&

compiler/testData/codegen/box/package/checkCast.kt

@@ -1,5 +1,5 @@
 class C(val x: Int) {
-  fun equals(rhs: Any?): Boolean {
+  override fun equals(rhs: Any?): Boolean {
     if (rhs is C) {
       val rhsC = rhs as C
       return rhsC.x == x

compiler/testData/codegen/box/typeMapping/hashable.kt

@@ -1,6 +0,0 @@
-fun foo(): Hashable = 1
-
-fun box(): String {
-    if (foo() == 1) return "OK"
-    return "Fail"
-}