build: switch to Kconfig

build: switch to Kconfig

The make_device_config.sh script is replaced by minikconf, which
is modified to support the same command line as its predecessor.

The roots of the parsing are default-configs/*.mak, Kconfig.host and
hw/Kconfig.  One difference with make_device_config.sh is that all symbols
have to be defined in a Kconfig file, including those coming from the
configure script.  This is the reason for the Kconfig.host file introduced
in the previous patch. Whenever a file in default-configs/*.mak used
$(...) to refer to a config-host.mak symbol, this is replaced by a
Kconfig dependency; this part must be done already in this patch
for bisectability.

Signed-off-by: Paolo Bonzini <[email protected]>
Signed-off-by: Yang Zhong <[email protected]>
Acked-by: Thomas Huth <[email protected]>
Message-Id: <20190123065618[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>