Fix merge error from 10.0

Item_func_sysconst behaves as a non-constant function during prepared statements and view creation and constant otherwise. Current condition implied the opposite.

Author: cvicentiu

sql/item_strfunc.cc

@@ -2339,7 +2339,7 @@ Item *Item_func_sysconst::safe_charset_converter(THD *thd, CHARSET_INFO *tocs)
 
  Return the identical item during view creation and prepare.
  */
- if (!thd->lex->is_ps_or_view_context_analysis())
+ if (thd->lex->is_ps_or_view_context_analysis())
  return this;
  return const_charset_converter(thd, tocs, true, fully_qualified_func_name());
 }