Remove dead code in ar_copy

All of the callers of ar_copy guarantee that hash2 has an ar table,
so we don't need the logic to handle the case when hash2 doesn't have
an ar table.

hash.c

@@ -1199,9 +1199,8 @@ static ar_table*
 ar_copy(VALUE hash1, VALUE hash2)
 {
     ar_table *old_tab = RHASH_AR_TABLE(hash2);
-
-    if (old_tab != NULL) {
     ar_table *new_tab = RHASH_AR_TABLE(hash1);
+
     if (new_tab == NULL) {
         new_tab = (ar_table*) rb_transient_heap_alloc(hash1, sizeof(ar_table));
         if (new_tab != NULL) {
@@ -1212,6 +1211,7 @@ ar_copy(VALUE hash1, VALUE hash2)
             new_tab = (ar_table*)ruby_xmalloc(sizeof(ar_table));
         }
     }
+
     *new_tab = *old_tab;
     RHASH(hash1)->ar_hint.word = RHASH(hash2)->ar_hint.word;
     RHASH_AR_TABLE_BOUND_SET(hash1, RHASH_AR_TABLE_BOUND(hash2));
@@ -1219,25 +1219,9 @@ ar_copy(VALUE hash1, VALUE hash2)
     hash_ar_table_set(hash1, new_tab);
 
     rb_gc_writebarrier_remember(hash1);
+
     return new_tab;
 }
-    else {
-        RHASH_AR_TABLE_BOUND_SET(hash1, RHASH_AR_TABLE_BOUND(hash2));
-        RHASH_AR_TABLE_SIZE_SET(hash1, RHASH_AR_TABLE_SIZE(hash2));
-
-        if (RHASH_TRANSIENT_P(hash1)) {
-            RHASH_UNSET_TRANSIENT_FLAG(hash1);
-        }
-        else if (RHASH_AR_TABLE(hash1)) {
-            ruby_xfree(RHASH_AR_TABLE(hash1));
-        }
-
-        hash_ar_table_set(hash1, NULL);
-
-        rb_gc_writebarrier_remember(hash1);
-        return old_tab;
-    }
-}
 
 static void
 ar_clear(VALUE hash)