Standard locale functions.
Set the app's locale for a category of routines.
setlocale can be used to:
set the app's locale to a specific locale:
set the app's locale to the system locale:
get the app's curent locale:
Currently, we only support two categories: LC_ALL and LC_TIME
The category of routines for which to set the locale
The ISO formatted locale to use, or "" for the system locale
the locale after the change is applied, NULL on failure (e.g. unsuported category)