start udhcpc with background option

package/busybox/Makefile

@@ -5,7 +5,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=		busybox
 PKG_VERSION:=		1.21.1
-PKG_RELEASE:=		2
+PKG_RELEASE:=		3
 PKG_MD5SUM:=		795394f83903b5eec6567d51eebb417e
 PKG_DESCR:=		core utilities for embedded systems
 PKG_SECTION:=		base

package/busybox/config/networking/Config.in

@@ -1017,7 +1017,7 @@ source package/busybox/config/networking/udhcp/Config.in
 
 config BUSYBOX_IFUPDOWN_UDHCPC_CMD_OPTIONS
 	string "ifup udhcpc command line options"
-	default "-R -n"
+	default "-R -b"
 	depends on BUSYBOX_IFUPDOWN && BUSYBOX_UDHCPC
 	help
 	  Command line options to pass to udhcpc from ifup.

package/busybox/config/util-linux/Config.in

@@ -69,6 +69,7 @@ config BUSYBOX_FEATURE_MDEV_LOAD_FIRMWARE
 	  These devices will request userspace look up the files in
 	  /lib/firmware/ and if it exists, send it to the kernel for
 	  loading into the hardware.
+
 config BUSYBOX_REV
 	bool "rev"
 	default n