coreutils: fixed build at native stages by setting FORCE_UNSAFE_CONFIGURE=1

Note:

At native stages the configure script is bailing out telling us that running
configure as root is a bad thing, and we need to set FORCE_UNSAFE_CONFIGURE=1
to bypass this check.

base/coreutils/coreutils.conf

@@ -29,6 +29,13 @@ for x in $(match_source_file -p patch); do
 	var_append patchfiles ' ' "$x"
 done
 
+# at native stages the configure script is bailing out telling us that running
+# configure as root is a bad thing, and we need to set FORCE_UNSAFE_CONFIGURE=1
+# to bypass this check.
+if atstage native; then
+	var_insert configprefix ' ' "FORCE_UNSAFE_CONFIGURE=1"
+fi
+
 # install libstdbuf.so into /usr/lib/coreutils instead of /usr/libexec/coreutils
 var_append extraconfopt ' ' "--libexecdir=$libdir"