Locale lookup doesn't seem to be working with full region code

[therealmate]

Description

Locale lookup appears to be too strict, it doesn't accept just hu.ftl, it needs the hyphen also (hu-HU.ftl). Uutils should just fall back to hu.ftl

Steps to reproduce

1. git clone https://github.com/uutils/coreutils-l10n
2. sudo cp uu/users/locales/hu.ftl /usr/share/locales/users/hu.ftl
3. LANG=hu_HU.UTF-8 uu-users --help (not localized)
4. sudo cp uu/users/locales/hu.ftl /usr/share/locales/users/hu-HU.ftl
5. LANG=hu_HU.UTF-8 uu-users --help (localized)

Locale output:

LC_CTYPE="hu_HU.UTF-8"
LC_NUMERIC="hu_HU.UTF-8"
LC_TIME="hu_HU.UTF-8"
LC_COLLATE="hu_HU.UTF-8"
LC_MONETARY="hu_HU.UTF-8"
LC_MESSAGES="hu_HU.UTF-8"
LC_PAPER="hu_HU.UTF-8"
LC_NAME="hu_HU.UTF-8"
LC_ADDRESS="hu_HU.UTF-8"
LC_TELEPHONE="hu_HU.UTF-8"
LC_MEASUREMENT="hu_HU.UTF-8"
LC_IDENTIFICATION="hu_HU.UTF-8"
LC_ALL=