modem-manager: select libgudev, if systemd is enabled

When eudev is used as the udev provider, libgudev is automatically
provided as it is part of eudev. However, when systemd is used as
the udev provider, libgudev is not provided, and needs to be built
separately. This is why we select the libgudev package only if
systemd is used.

Fixes: http://autobuild.buildroot.net/results/d59/d597a81271a082c8252e2333906815c437b6576d/

While at it, group the existing dbus select together with the dbus-glib
select, so that all "select" statements are together.

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Reviewed-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/modem-manager/Config.in

@@ -1,11 +1,12 @@
 config BR2_PACKAGE_MODEM_MANAGER
 	bool "modemmanager"
 	depends on BR2_PACKAGE_HAS_UDEV
-	select BR2_PACKAGE_DBUS
 	depends on BR2_USE_WCHAR # libglib2 and gnutls
 	depends on BR2_TOOLCHAIN_HAS_THREADS # dbus, libglib2
 	depends on BR2_USE_MMU # dbus
+	select BR2_PACKAGE_DBUS
 	select BR2_PACKAGE_DBUS_GLIB
+	select BR2_PACKAGE_LIBGUDEV if BR2_INIT_SYSTEMD
 	help
 	  ModemManager is a DBus-activated daemon which controls mobile
 	  broadband (2G/3G/4G) devices and connections.

package/modem-manager/modem-manager.mk

@@ -12,6 +12,10 @@ MODEM_MANAGER_LICENSE_FILES = COPYING
 MODEM_MANAGER_DEPENDENCIES = host-pkgconf udev dbus-glib host-intltool
 MODEM_MANAGER_INSTALL_STAGING = YES
 
+ifeq ($(BR2_INIT_SYSTEMD),y)
+MODEM_MANAGER_DEPENDENCIES += libgudev
+endif
+
 ifeq ($(BR2_PACKAGE_MODEM_MANAGER_LIBQMI),y)
 MODEM_MANAGER_DEPENDENCIES += libqmi
 MODEM_MANAGER_CONF_OPTS += --with-qmi