stdint types all the way!

Change-Id: I4e4ef3a2002fc59ebd9097087f150eaf3f2a7e08
diff --git a/runtime/gc/accounting/atomic_stack.h b/runtime/gc/accounting/atomic_stack.h
index 2c72ba1..929a1d2 100644
--- a/runtime/gc/accounting/atomic_stack.h
+++ b/runtime/gc/accounting/atomic_stack.h
@@ -213,7 +213,7 @@
     mem_map_.reset(MemMap::MapAnonymous(name_.c_str(), NULL, capacity_ * sizeof(T),
                                         PROT_READ | PROT_WRITE, false, &error_msg));
     CHECK(mem_map_.get() != NULL) << "couldn't allocate mark stack.\n" << error_msg;
-    byte* addr = mem_map_->Begin();
+    uint8_t* addr = mem_map_->Begin();
     CHECK(addr != NULL);
     debug_is_sorted_ = true;
     begin_ = reinterpret_cast<T*>(addr);