intltool-update doesn't handle AC_INIT(/m4_esyscmd_s) (it does with m4_esyscmd)

We have a configure.ac such as:
AC_INIT([chronojump], [m4_esyscmd_s([git describe])])

which seems to be quite standard. Other projects had the same problem like here: https://mail.gnome.org/archives/commits-list/2012-March/msg08988.html

I'd prefer to not have to use their workaround to make sure that this is multi-platform.

The problem is that intltool-update doesn't support m4_esyscmd_s but it supports m4_esyscmd.

I'm attaching a patch.