Removed extraneous C++-style comment.
diff --git a/upb/port_def.inc b/upb/port_def.inc
index 0d84156..2dafc3d 100644
--- a/upb/port_def.inc
+++ b/upb/port_def.inc
@@ -182,7 +182,6 @@
 #define UPB_NAN (0.0 / 0.0)
 #endif
 
-// User code should use macros instead of functions.
 #if defined(__SANITIZE_ADDRESS__)
 #define UPB_ASAN 1
 #ifdef __cplusplus