Fixed LP bug#695304.

The bug was the result of a bad merge maria-5.2-wl21 -> 5.3.

mysql-test/r/optimizer_switch.result

@@ -97,3 +97,6 @@ select @@optimizer_switch;
 @@optimizer_switch
 index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=off,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on,subquery_cache=on,mrr_sort_keys=on,outer_join_with_cache=off,semijoin_with_cache=off,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on
 set optimizer_switch=default;
+select @@optimizer_switch;
+@@optimizer_switch
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on,subquery_cache=on,mrr_sort_keys=on,outer_join_with_cache=off,semijoin_with_cache=off,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on,table_elimination=on

mysql-test/t/optimizer_switch.test

@@ -110,4 +110,7 @@ set optimizer_switch='default,materialization=off,loosescan=off';
 select @@optimizer_switch; 
 set optimizer_switch=default;
 
-
+#
+# Bug #695304: invalid default setting for optimizer_switch
+#
+select @@optimizer_switch;

sql/mysqld.cc

@@ -470,7 +470,7 @@ static const char *sql_mode_str= "OFF";
 static const char *optimizer_switch_str="index_merge=on,index_merge_union=on,"
                                         "index_merge_sort_union=on,"
                                         "index_merge_intersection=on,"
-                                        "index_merge_sort_intersection=off"
+                                        "index_merge_sort_intersection=off,"
                                         "index_condition_pushdown=on,"
                                         "firstmatch=on,"
                                         "loosescan=on,"