Unfold automake variables into multiple lines for maintainability

Makefile.am

@@ -2,8 +2,11 @@ AUTOMAKE_OPTIONS = foreign
 ACLOCAL_AMFLAGS = -I m4
 SUBDIRS = src $(UDEV_SUB) $(SYSTEMD_SUB) docs
 
-EXTRA_DIST = docs COPYING.GPLv2 COPYING.GPLv3
+EXTRA_DIST = \
+	docs \
+	COPYING.GPLv2 \
+	COPYING.GPLv3
 
-DISTCHECK_CONFIGURE_FLAGS =				\
+DISTCHECK_CONFIGURE_FLAGS = \
 	--with-udevrulesdir=$$dc_install_base/$(udevrulesdir) \
 	--with-systemdsystemunitdir=$$dc_install_base/$(systemdsystemunitdir)

src/Makefile.am

@@ -1,17 +1,30 @@
-AM_CPPFLAGS = -I$(top_srcdir)/include -I$(top_srcdir)
+AM_CPPFLAGS = \
+	-I$(top_srcdir)/include \
+	-I$(top_srcdir)
 
-AM_CFLAGS = $(GLOBAL_CFLAGS) $(libplist_CFLAGS) $(libusb_CFLAGS) $(libimobiledevice_CFLAGS)
-AM_LDFLAGS = $(libplist_LIBS) $(libusb_LIBS) $(libimobiledevice_LIBS) $(libpthread_LIBS)
+AM_CFLAGS = \
+	$(GLOBAL_CFLAGS) \
+	$(libplist_CFLAGS) \
+	$(libusb_CFLAGS) \
+	$(libimobiledevice_CFLAGS)
+
+AM_LDFLAGS = \
+	$(libplist_LIBS) \
+	$(libusb_LIBS) \
+	$(libimobiledevice_LIBS) \
+	$(libpthread_LIBS)
 
 sbin_PROGRAMS = usbmuxd
 
 usbmuxd_CFLAGS = $(AM_CFLAGS)
 usbmuxd_LDFLAGS = $(AM_LDFLAGS) -no-undefined
-usbmuxd_SOURCES = client.c client.h \
-		device.c device.h \
-		preflight.c preflight.h \
-		log.c log.h \
-		usbmuxd-proto.h usb.c usb.h \
-		utils.c utils.h \
-		conf.c conf.h \
-		main.c
+usbmuxd_SOURCES = \
+	client.c client.h \
+	device.c device.h \
+	preflight.c preflight.h \
+	log.c log.h \
+	usbmuxd-proto.h \
+	usb.c usb.h \
+	utils.c utils.h \
+	conf.c conf.h \
+	main.c