busybox: update to version 1.34.0

Update busybox to version 1.34.0

* Remove upstreamed patches (205, 530, 540)

* Remove one old patch that does not apply any more. (203)
  That was originally introduced in 2008 with 563d2345,
  but does not apply after busybox restructuring with
  https://git.busybox.net/busybox/commit/networking/udhcp/dhcpc.c?h=1_34_stable&id=e6007c4911c3ea26925f9473b9f156a692585f30
  and
  https://git.busybox.net/busybox/commit/networking/udhcp/dhcpc.c?h=1_34_stable&id=1c7253726fcbab09917f143f0b703efbd2df55c3

* Refresh config and patches.

* Backport upstream fixes for
   - MIPS compilation breakage and
   - process substitution regression

Config refresh:

Refresh commands, run after busybox is first built once:

cd utils/busybox/
cd config/
../convert_menuconfig.pl ../../../../build_dir/target-aarch64_cortex-a53_musl/busybox-default/busybox-1.34.0
cd ..
./convert_defaults.pl < ../../../build_dir/target-aarch64_cortex-a53_musl/busybox-default/busybox-1.34.0/.config > Config-defaults.in

Manual edits needed afterward:

* Config-defaults.in:  OpenWrt config symbol IPV6 logic applied to
  BUSYBOX_DEFAULT_FEATURE_IPV6
* Config-defaults.in:  OpenWrt configTARGET_bcm53xx logic applied to
  BUSYBOX_DEFAULT_TRUNCATE (commit 547f1ec2)
* Config-defaults.in:  OpenWrt logic applied to
  BUSYBOX_DEFAULT_LOGIN_SESSION_AS_CHILD (commit dc929174)
  BUSYBOX_DEFAULT_UDHCPC_DEFAULT_INTERFACE (just "")
* config/editors/Config.in: Add USE_GLIBC dependency to
  BUSYBOX_CONFIG_FEATURE_VI_REGEX_SEARCH (commit f1410902)
* config/shell/Config.in : change at "Options common to all shells"  the symbol
  SHELL_ASH  -->  BUSYBOX_CONFIG_SHELL_ASH
   (discussion in http://lists.openwrt.org/pipermail/openwrt-devel/2021-January/033140.html


     Apparently our script does not see the hidden option while
     prepending config options with "BUSYBOX_CONFIG_" which leads to a
     missed dependency when the options are later evaluated.)
* Edit Config.in files by adding quotes to sourced items in
  config/Config.in, config/networking/Config.in and config/util-linux/Config.in (commit 1da014fc)

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