Fix the Mac build on x86-64.

Change-Id: I4ed3783a96d844de0b0a295df26d0a48c02a3726
diff --git a/runtime/entrypoints/quick/quick_alloc_entrypoints.cc b/runtime/entrypoints/quick/quick_alloc_entrypoints.cc
index 3301254..dde74de 100644
--- a/runtime/entrypoints/quick/quick_alloc_entrypoints.cc
+++ b/runtime/entrypoints/quick/quick_alloc_entrypoints.cc
@@ -154,10 +154,12 @@
 }
 
 // Generate the entrypoint functions.
+#if !defined(__APPLE__) || !defined(__LP64__)
 GENERATE_ENTRYPOINTS(_dlmalloc);
 GENERATE_ENTRYPOINTS(_rosalloc);
 GENERATE_ENTRYPOINTS(_bump_pointer);
 GENERATE_ENTRYPOINTS(_tlab);
+#endif
 
 static bool entry_points_instrumented = false;
 static gc::AllocatorType entry_points_allocator = gc::kAllocatorTypeDlMalloc;
@@ -172,6 +174,7 @@
 
 void ResetQuickAllocEntryPoints(QuickEntryPoints* qpoints) {
   switch (entry_points_allocator) {
+#if !defined(__APPLE__) || !defined(__LP64__)
     case gc::kAllocatorTypeDlMalloc: {
       SetQuickAllocEntryPoints_dlmalloc(qpoints, entry_points_instrumented);
       break;
@@ -190,6 +193,7 @@
       SetQuickAllocEntryPoints_tlab(qpoints, entry_points_instrumented);
       break;
     }
+#endif
     default: {
       LOG(FATAL) << "Unimplemented";
     }