USER, DATABASE and VERSION functions returns now IMPLICIT coercibility

sql/item_create.cc

@@ -437,7 +437,7 @@ Item *create_func_version(void)
 {
   return new Item_string(NullS,server_version, 
 			 (uint) strlen(server_version),
-			 system_charset_info);
+			 system_charset_info, Item::COER_IMPLICIT);
 }
 
 Item *create_func_weekday(Item* a)

sql/item_strfunc.h

@@ -333,7 +333,7 @@ public:
 class Item_func_database :public Item_str_func
 {
 public:
-  Item_func_database() {}
+  Item_func_database() { coercibility= COER_IMPLICIT; }
   String *val_str(String *);
   void fix_length_and_dec() 
   { 
@@ -346,7 +346,7 @@ public:
 class Item_func_user :public Item_str_func
 {
 public:
-  Item_func_user() {}
+  Item_func_user() { coercibility= COER_IMPLICIT; }
   String *val_str(String *);
   void fix_length_and_dec() 
   {