util/kconfig: Uprev to Linux 5.13's kconfig

This was originally several commits that had to be squashed into one
because the intermediate states weren't able to build coreboot:

 - one to remove everything that wasn't our own code, leaving only
   regex.[ch], toada.c, description.md and Makefile.inc.
 - one to copy in Linux 5.13's scripts/kconfig and adapt Makefile.inc
   to make the original Makefile work again.
 - adapt abuild to use olddefconfig, simplifying matters.
 - apply patches in util/kconfig/patches.
 - Some more adaptations to the libpayload build system.

The patches are now in util/kconfig/patches/, reverse applying them
should lead to a util/kconfig/ tree that contains exactly the Linux
version + our own 5 files.

Change-Id: Ia0e8fe4e9022b278f34ab113a433ef4d45e5c355
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37152
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>

util/kconfig/patches/series

@@ -0,0 +1,12 @@
+0001-Kconfig-Add-KCONFIG_STRICT-mode.patch
+0002-Kconfig-Change-symbol-override-from-warning-to-notic.patch
+0003-util-kconfig-conf.c-Fix-newline-in-error-printf.patch
+0004-src-util-Use-NULL-instead-of-0-for-pointer.patch
+0005-util-kconfig-Ignore-extra-symbols-in-configs-instead.patch
+0006-util-kconfig-Set-parameter-of-mkdir-to-only-one-for-.patch
+0007-kconfig-Allow-KCONFIG_STRICT-outside-of-confdata.c.patch
+0008-kconfig-Add-wildcard-support-for-source.patch
+0009-util-kconfig-Allow-emitting-false-booleans-into-kconfig-output.patch
+0010-reenable-source-in-choice.patch
+0011-remove-include-config-hardcodes.patch
+0012-safer-tmpfiles.patch