busybox: update to 1.31.0

* Update busybox to version 1.31.0.
    New applets: ts, i2ctransfer
    New (restored) feature: error/info levels in syslog messages.
    Leave new features disabled by default.
* Refresh patches
* Remove patch that was backported from upstream

Config refreshed with commands below, after which the OpenWrt specific
config defaults (ipv6, login session child) were corrected:

  make package/busybox/compile   (to populate the build_dir)

  cd package/utils/busybox/config/
  ../convert_menuconfig.pl ../../../../build_dir/target-mips_24kc_musl/busybox-1.31.0

  cd package/utils/busybox
  ./convert_defaults.pl < ../../../build_dir/target-mips_24kc_musl/busybox-1.31.0/.config > Config-defaults.in

Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>

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

@@ -473,6 +473,17 @@ config BUSYBOX_CONFIG_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_CONFIG_FEATURE_MDEV_DAEMON
+	bool "Support daemon mode"
+	default BUSYBOX_DEFAULT_FEATURE_MDEV_DAEMON
+	depends on BUSYBOX_CONFIG_MDEV
+	help
+	Adds the -d option to run mdev in daemon mode handling hotplug
+	events from the kernel like udev. If the system generates many
+	hotplug events this mode of operation will consume less
+	resources than registering mdev as hotplug helper or using the
+	uevent applet.
 config BUSYBOX_CONFIG_MESG
 	bool "mesg (1.4 kb)"
 	default BUSYBOX_DEFAULT_MESG