updated comment

--- a/src/HOL/UNITY/Mutex.ML	Fri May 21 10:58:47 1999 +0200
+++ b/src/HOL/UNITY/Mutex.ML	Fri May 21 10:59:41 1999 +0200
@@ -6,7 +6,7 @@
 Based on "A Family of 2-Process Mutual Exclusion Algorithms" by J Misra
 *)
 
-(*split_all_tac causes a big blow-up*)
+(*record_split_name causes a BIG blow-up (doubles the run-time)*)
 claset_ref() := claset() delSWrapper record_split_name;
 
 Addsimps [Mutex_def RS def_prg_Init];