[gnome-photos] build: Let git.mk ignore the M4 sources pulled in my Libtool

[Debarshi Ray <debarshir src gnome org>]

commit 687d3de1b4777d0efb322c4752c0cbce1acd505e
Author: Debarshi Ray <debarshir gnome org>
Date:   Mon Oct 30 13:56:24 2017 +0100

    build: Let git.mk ignore the M4 sources pulled in my Libtool

 Makefile.am |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index ab4cf26..538e50d 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -27,6 +27,7 @@ DISTCLEANFILES = \
 
 MAINTAINERCLEANFILES = \
        $(GITIGNORE_MAINTAINERCLEANFILES_M4_GETTEXT) \
+       $(GITIGNORE_MAINTAINERCLEANFILES_M4_LIBTOOL) \
        $(srcdir)/AUTHORS \
        $(srcdir)/INSTALL \
        $(srcdir)/ar-lib \
@@ -49,8 +50,6 @@ MAINTAINERCLEANFILES = \
 
 GITIGNOREFILES = \
        config \
-       m4/libtool.m4 \
-       m4/lt* \
        $(NULL)
 
 AUTHORS: