Cleanup: reserve C++ comments for disabled code

Use C comments for plain text.

source/blender/depsgraph/intern/builder/deg_builder_rna.cc

@@ -153,8 +153,8 @@ bool RNANodeQuery::contains(const char *prop_identifier, const char *rna_path_co
     return false;
   }
 
-  // If substr != prop_identifier, it means that the substring is found further in prop_identifier,
-  // and that thus index -1 is a valid memory location.
+  /* If substr != prop_identifier, it means that the substring is found further in prop_identifier,
+   * and that thus index -1 is a valid memory location. */
   const bool start_ok = substr == prop_identifier || substr[-1] == '.';
   if (!start_ok) {
     return false;