[Runtime] Fix up the URC overflow test and support code after merging the latest master.

rdar://problem/33765960

Author: mikeash

stdlib/public/SwiftShims/RefCount.h

@@ -1277,11 +1277,6 @@ class RefCounts {
   // Note that this is not equal to the number of outstanding weak pointers.
   uint32_t getWeakCount() const;
 
-  HeapObjectSideTableEntry *getSideTable() const {
-    auto bits = refCounts.load(SWIFT_MEMORY_ORDER_CONSUME);
-    return bits.getSideTable();
-  }
-
   private:
   HeapObject *getHeapObject();
 
@@ -1469,7 +1464,7 @@ class HeapObjectSideTableEntry {
     return refCounts.getWeakCount();
   }
 
-  HeapObjectSideTableEntry *getSideTable() {
+  void *getSideTable() {
     return refCounts.getSideTable();
   }
 };

unittests/runtime/LongTests/LongRefcounting.cpp

@@ -1078,7 +1078,7 @@ TEST(LongRefcountingTest, lifecycle_live_deiniting_urc_overflow_to_side) {
       swift_unownedRetain(object);
     }
 
-    side = object->refCounts.getSideTable();
+    side = reinterpret_cast<HeapObjectSideTableEntry *>(object->refCounts.getSideTable());
     EXPECT_ALLOCATED(side);
 
     for (uint64_t i = 0; i < urcOverflowCount; i++) {