busybox: enable unicode support

While creating and deleting files with unicode or other
encodings works, it's annoying when ls and other core utils
show questionmarks instead of the unicode characters.
In 2019, it's quite common that users of embedded devices
based on yocto need unicode support. Debugging a box with
unicode encoded file names is a bit annoying when core utils
from busybox don't support them.

The unicode config fragment has the same config as Debian in their
deb and udeb builds of version 1:1.30.1-4.

If developers do not want this or other default yocto features in busybox,
or optimize the configuration for size, then they likely run a completely
custom configuration. Thus I think it's safe to enable unicode support
by default.

(From OE-Core rev: a48438422dbe64095bdb379c20428ba87e2a0e99)

Signed-off-by: Mikko Rapeli <mikko.rapeli@bmw.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/busybox/busybox/unicode.cfg

@@ -0,0 +1,10 @@
+CONFIG_UNICODE_SUPPORT=y
+# CONFIG_UNICODE_USING_LOCALE is not set
+CONFIG_FEATURE_CHECK_UNICODE_IN_ENV=y
+CONFIG_SUBST_WCHAR=63
+CONFIG_LAST_SUPPORTED_WCHAR=767
+CONFIG_UNICODE_COMBINING_WCHARS=y
+CONFIG_UNICODE_WIDE_WCHARS=y
+# CONFIG_UNICODE_BIDI_SUPPORT is not set
+# CONFIG_UNICODE_NEUTRAL_TABLE is not set
+# CONFIG_UNICODE_PRESERVE_BROKEN is not set

meta/recipes-core/busybox/busybox_1.31.0.bb

@@ -37,6 +37,7 @@ SRC_URI = "http://www.busybox.net/downloads/busybox-${PV}.tar.bz2;name=tarball \
            ${@["", "file://init.cfg"][(d.getVar('VIRTUAL-RUNTIME_init_manager') == 'busybox')]} \
            ${@["", "file://mdev.cfg"][(d.getVar('VIRTUAL-RUNTIME_dev_manager') == 'busybox-mdev')]} \
            file://syslog.cfg \
+           file://unicode.cfg \
            file://inittab \
            file://rcS \
            file://rcK \