multi-line ACLOCAL_AMFLAGS isn't supported by autoreconf.
It will cause configure error as follow.

  aclocal: error: non-option arguments are not accepted: '\'.

Signed-off-by: Bian Naimeng <biannm@cn.fujitsu.com>

diff -Nurp imsettings-1.7.1.orig/Makefile.am imsettings-1.7.1/Makefile.am
--- imsettings-1.7.1.orig/Makefile.am	2013-02-08 11:33:59.000000000 +0900
+++ imsettings-1.7.1/Makefile.am	2015-06-24 14:15:32.070000007 +0900
@@ -1,7 +1,7 @@
 NULL =
 SUBDIRS = data imsettings imsettings-daemon backends utils po tests docs
 
-ACLOCAL_AMFLAGS = -Im4macros
+ACLOCAL_AMFLAGS = -I m4macros $(NULL)
 
 CONFIGURE_DEPENDENCIES =		\
 	requires			\
