Fix missing semicolon with tracing enabled. (#3891)

diff --git a/iree/vm/stack.h b/iree/vm/stack.h
index 6c50e7f..e5722a0 100644
--- a/iree/vm/stack.h
+++ b/iree/vm/stack.h
@@ -87,7 +87,7 @@
   // code), etc.
   iree_vm_source_offset_t pc;
 
-  IREE_TRACE(iree_zone_id_t trace_zone)
+  IREE_TRACE(iree_zone_id_t trace_zone);
 } iree_vm_stack_frame_t;
 
 // Returns the implementation-defined frame storage associated with |frame|.