[gjs] build: Add comment for future maintainers

[Philip Chimento <pchimento src gnome org>]

commit 7b801fc5a2556a6b3d99ec1a7d51a06223e344a3
Author: Philip Chimento <philip chimento gmail com>
Date:   Mon Sep 26 22:45:10 2016 -0700

    build: Add comment for future maintainers
    
    The ACLOCAL_AMFLAGS variable is obsolete but harmless starting with
    Automake 1.13, but will not be supported in 2.0. Leave a note so that
    future maintainers will know when to remove it.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=772027

 Makefile.am |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index e8e9752..4b1538f 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -14,6 +14,7 @@ EXTRA_DIST =
 TEST_PROGS =
 check_PROGRAMS = $(TEST_PROGS)
 INTROSPECTION_GIRS =
+## ACLOCAL_AMFLAGS can be removed for Automake 1.13
 ACLOCAL_AMFLAGS = -I m4
 AM_CXXFLAGS = $(WARN_CXXFLAGS)
 AM_CPPFLAGS = -DG_LOG_DOMAIN=\"Gjs\"