Fixed BUG#6898: Stored procedure crash if GOTO statements exist

Bug in the optimizer caused an infinite loop for weird code.

mysql-test/r/sp.result

@@ -2958,4 +2958,13 @@ select @x|
 set global query_cache_size = @qcs1|
 delete from t1|
 drop function bug9902|
+drop procedure if exists bug6898|
+create procedure bug6898()
+begin
+goto label1;
+label label1;
+begin end;
+goto label1;
+end|
+drop procedure bug6898|
 drop table t1,t2;

mysql-test/t/sp.test

@@ -3628,6 +3628,22 @@ delete from t1|
 drop function bug9902|
 
 
+#
+# BUG#6898: Stored procedure crash if GOTO statements exist
+#
+--disable_warnings
+drop procedure if exists bug6898|
+--enable_warnings
+create procedure bug6898()
+begin
+  goto label1;
+  label label1;
+  begin end;
+  goto label1;
+end|
+drop procedure bug6898|
+
+
 #
 # BUG#NNNN: New bug synopsis
 #

sql/sp_head.cc

@@ -1499,7 +1499,7 @@ sp_instr_jump::opt_shortcut_jump(sp_head *sp, sp_instr *start)
   {
     uint ndest;
 
-    if (start == i)
+    if (start == i || this == i)
       break;
     ndest= i->opt_shortcut_jump(sp, start);
     if (ndest == dest)