git-sh-i18n.sh: add no-op gettext() and eval_gettext() wrappers

Add a no-op wrapper library for Git's shell scripts. To split up the
gettext series I'm first submitting patches to gettextize the source
tree before I add any of the Makefile and Shell library changes needed
to actually use them.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Makefile b/Makefile
index 87c83cb..83889f3 100644
--- a/Makefile
+++ b/Makefile
@@ -381,6 +381,7 @@
 SCRIPT_LIB += git-rebase--interactive
 SCRIPT_LIB += git-rebase--merge
 SCRIPT_LIB += git-sh-setup
+SCRIPT_LIB += git-sh-i18n
 
 SCRIPT_PERL += git-add--interactive.perl
 SCRIPT_PERL += git-difftool.perl