treewide: surround Kconfig file paths with double quotes ...

Based on Linux commit 8636a1f

This will be needed when you sync Kconfig with Linux 5.0 or later.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

kconfig: sync to Linux 4.20 ...

The previous sync was commit 18895514dc5e ("kconfig: update to
v3.18-rc6").

Some commits were applied on top of that since then, but equivalent
fixups were done in Linux.

So, this commit overwrites everything scripts/kconfig/ with the one
from Linux 4.20

Highlights:

 - 'silentoldconfig' has been renamed to 'syncconfig'
   (the top Makefile needs to be adjusted)

 - 'testconfig' target has been added for unit-tests
   (the top Makefile needs to export PYTHON3 because
    the test frame relies on Python3 and pytest)

 - The perfect hash table generated by gperf has been removed

 - The localization support has been removed

 - The 'option env=VAR' has been replaced with more generic
   variable reference syntax $(VAR)
   (./Kconfig and common/Kconfig need to be adjusted)

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

kconfig: include common Kconfig files from top-level Kconfig ...

Based on this linux kernel commit:

> commit 1572497
> Author: Christoph Hellwig <hch@lst.de>
> Date:   Tue Jul 31 13:39:30 2018 +0200
>
>     kconfig: include common Kconfig files from top-level Kconfig

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

scripts: create a separate section for host tools ...

This allows to enable host tools even if they are not needed for the
current configuration to improve compile coverage and simplify packaging
these tools. The conversion doesn't cover all tools available but can be
extended later.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

menuconfig: Show "Barebox", not "Linux" at the top. ...

The menuconfig configures Barebox, not the Linux kernel, so no reason
to print "Linux" there.

Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

kconfig: syn with linux kernel v2.6.38-rc3 ...

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>