i18n: git-submodule $errmsg messages

Gettextize warning messages stored in the $errmsg variable using
eval_gettext interpolation. This is explicitly tested for so we
need to skip a portion of a test with test_i18ncmp.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/git-submodule.sh b/git-submodule.sh
index 60ea58e..5de34e4 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -678,13 +678,13 @@
 		total_commits=
 		case "$missing_src,$missing_dst" in
 		t,)
-			errmsg="  Warn: $name doesn't contain commit $sha1_src"
+			errmsg="$(eval_gettext "  Warn: \$name doesn't contain commit \$sha1_src")"
 			;;
 		,t)
-			errmsg="  Warn: $name doesn't contain commit $sha1_dst"
+			errmsg="$(eval_gettext "  Warn: \$name doesn't contain commit \$sha1_dst")"
 			;;
 		t,t)
-			errmsg="  Warn: $name doesn't contain commits $sha1_src and $sha1_dst"
+			errmsg="$(eval_gettext "  Warn: \$name doesn't contain commits \$sha1_src and \$sha1_dst")"
 			;;
 		*)
 			errmsg=