Bug#43201 : Stack overrun when running sp-error test.

It appears that stack overflow checks for recusrive stored procedure
calls, that run in the normal server, did not work in embedded and were
 dummified with preprocessor magic( #ifndef EMBEDDED_SERVER ).
      
 The fix is to remove ifdefs, there is no reason not to run overflow checks
 and crash in deeply recursive calls. 
      
 Note: Start of the stack (thd->thread_stack variable) in embedded is not
necessarily exact but stil provides the best guess. Unless the caller of 
mysql_read_connect()   is already deep in the stack, thd->thread_stack 
variable should approximate stack  start address well.

sql/item_cmpfunc.cc

@@ -2865,9 +2865,7 @@ bool Item_func_case::fix_fields(THD *thd, Item **ref)
     buff should match stack usage from
     Item_func_case::val_int() -> Item_func_case::find_item()
   */
-#ifndef EMBEDDED_LIBRARY
   uchar buff[MAX_FIELD_WIDTH*2+sizeof(String)*2+sizeof(String*)*2+sizeof(double)*2+sizeof(longlong)*2];
-#endif
   bool res= Item_func::fix_fields(thd, ref);
   /*
     Call check_stack_overrun after fix_fields to be sure that stack variable
@@ -4081,9 +4079,7 @@ Item_cond::fix_fields(THD *thd, Item **ref)
   DBUG_ASSERT(fixed == 0);
   List_iterator<Item> li(list);
   Item *item;
-#ifndef EMBEDDED_LIBRARY
   uchar buff[sizeof(char*)];			// Max local vars in function
-#endif
   not_null_tables_cache= used_tables_cache= 0;
   const_item_cache= 1;
   /*