hog: Add suspend back-end selection

This patch series introduces back-end selection for HoG suspend drivers.
The default back-end is called "dummy", added for testing purpose only.
diff --git a/acinclude.m4 b/acinclude.m4
index 39b0a18..ed2d011 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -185,6 +185,7 @@
 	datafiles_enable=yes
 	telephony_driver=dummy
 	sap_driver=dummy
+	hog_suspend_driver=dummy
 	dbusoob_enable=no
 	wiimote_enable=no
 	gatt_enable=no
@@ -288,6 +289,12 @@
 		wiimote_enable=${enableval}
 	])
 
+	AC_ARG_WITH(gatt, AC_HELP_STRING([--with-hog-suspend=DRIVER], [select HoG suspend driver]), [
+		hog_suspend_driver=${withval}
+	])
+
+	AC_SUBST([HOG_SUSPEND_DRIVER], [suspend-${hog_suspend_driver}.c])
+
 	AC_ARG_ENABLE(gatt, AC_HELP_STRING([--enable-gatt], [enable gatt module]), [
 		gatt_enable=${enableval}
 	])