Re-enable the UTF-8 locale

On the fresh build straight from the CI, the `rousette` service was
crashing with an std::runtime_error:

 Could not set locale C.UTF-8

...which is expected, because that's the locale name that the service's
C++ code actually hardcodes :).

Fixes: 14498b76ca826437828c3d75afe205068e4736a6 (Remove systemd locale patch from our buildroot)
Fixes: https://gerrit.cesnet.cz/c/CzechLight/rousette/+/6413
Change-Id: I0a4e72f6dfb4ab9523ed92bd9d9210cf09e6fee2
Reported-by: Tomáš Pecka <tomas.pecka@cesnet.cz>
diff --git a/configs/czechlight_clearfog_defconfig b/configs/czechlight_clearfog_defconfig
index 09151d9..87840c0 100644
--- a/configs/czechlight_clearfog_defconfig
+++ b/configs/czechlight_clearfog_defconfig
@@ -19,6 +19,8 @@
 BR2_TARGET_GENERIC_GETTY_PORT="ttyS0"
 BR2_TARGET_GENERIC_GETTY_BAUDRATE_115200=y
 # BR2_TARGET_GENERIC_REMOUNT_ROOTFS_RW is not set
+BR2_ENABLE_LOCALE_WHITELIST="C en_US C.UTF-8 en_US.UTF-8"
+BR2_GENERATE_LOCALE="C.UTF-8 en_US.UTF-8"
 BR2_ROOTFS_USERS_TABLES="$(BR2_EXTERNAL_CZECHLIGHT_PATH)/board/czechlight/common/users"
 BR2_ROOTFS_OVERLAY="$(BR2_EXTERNAL_CZECHLIGHT_PATH)/board/czechlight/common/overlay/ $(BR2_EXTERNAL_CZECHLIGHT_PATH)/board/czechlight/clearfog/overlay/"
 BR2_ROOTFS_POST_BUILD_SCRIPT="$(BR2_EXTERNAL_CZECHLIGHT_PATH)/board/czechlight/clearfog/post_build.sh"