[NFC][scudo] Replace size_t with uptr

GitOrigin-RevId: 887dda5dcdcf4a273f9c2885d147066343efd5b0
diff --git a/memtag.h b/memtag.h
index cf1ec3b..ec4b698 100644
--- a/memtag.h
+++ b/memtag.h
@@ -110,7 +110,7 @@
 }
 
 class ScopedDisableMemoryTagChecks {
-  size_t PrevTCO;
+  uptr PrevTCO;
 
 public:
   ScopedDisableMemoryTagChecks() {