core: add a kconfig option to require an UTF8 locale on the host

This can be selected when we need the host to have an UTF-8 locale
(e.g. to build uClibc with support for locales).

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

Config.in

@@ -84,6 +84,11 @@ config BR2_HOSTARCH_NEEDS_IA32_LIBS
 config BR2_HOSTARCH_NEEDS_IA32_COMPILER
 	bool
 
+# Hidden boolean selected by packages that need the host to have an
+# UTF8 locale.
+config BR2_NEEDS_HOST_UTF8_LOCALE
+	bool
+
 source "arch/Config.in"
 
 menu "Build options"