Replace usage of non-portable `uselocale` with locale-dependent functions (FIXED)
When the OS doesn't support uselocale
(ex. NetBSD), the function is replaced with a dummy stub.
Replace nl_langinfo
with portable nl_langinfo_l
.
Introduce locale-dependent *gettext_l
functions.
This MR is the same as !108 (merged), but with a fix for crashes due to uninitialized locales + test.