i18n: git-submodule $update_module say + die messages

Gettextize $update_module say and die messages. These messages needed
to be split up to make them translatable.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t7406-submodule-update.sh b/t/t7406-submodule-update.sh
index 4f16fcc..60e33be 100755
--- a/t/t7406-submodule-update.sh
+++ b/t/t7406-submodule-update.sh
@@ -90,7 +90,7 @@
 	(cd super &&
 	  git submodule update > ../actual 2> ../actual.err
 	) &&
-	test_cmp expected actual &&
+	test_i18ncmp expected actual &&
 	! test -s actual.err
 '