kconfig: fix comment referring to old Makefiles

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200908094244.26327-1-pbonzini@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

Kconfig.host

@@ -1,6 +1,6 @@
 # These are "proxy" symbols used to pass config-host.mak values
-# down to Kconfig.  See also MINIKCONF_ARGS in the Makefile:
-# these two need to be kept in sync.
+# down to Kconfig.  See also kconfig_external_symbols in
+# meson.build: these two need to be kept in sync.
 
 config LINUX
     bool