at: ensure startup script is well installed

In case /etc/init.d does not exist.

[Peter: use install -D]
Signed-off-by: Lionel Landwerlin <llandwerlin@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

CHANGES

@@ -3,7 +3,7 @@
 	Ccache support reworked. Now used for both host and target
 	compilation, and cache is stored in ~/.buildroot-ccache.
 
-	Updated/fixed packages: busybox, dbus, cloop, cups,
+	Updated/fixed packages: at, busybox, dbus, cloop, cups,
 	gdk-pixbuf, hostapd, i2c-tools, libconfig, m4, openssh,
 	openssl, pango, qt, rsync, sdl_gfx, sdl_sound, udev, usbutils,
 	xz, zlib

package/at/at.mk

@@ -20,7 +20,7 @@ AT_CONF_OPT = \
 	SENDMAIL=/usr/sbin/sendmail
 
 define AT_INSTALL_INITSCRIPT
-	$(INSTALL) -m 0755 package/at/S99at $(TARGET_DIR)/etc/init.d/S99at
+	$(INSTALL) -m 0755 -D package/at/S99at $(TARGET_DIR)/etc/init.d/S99at
 endef
 
 AT_POST_INSTALL_TARGET_HOOKS += AT_INSTALL_INITSCRIPT