build system: fix build of kconfig on Darwin

Of course busybox cannot be used on Darwin (Mac OS X), but it can be
cross-compiled for Linux there. Cross-compilation still requires kconfig
to be built as native host tool.

Signed-off-by: Bernhard Walle <bernhard@bwalle.de>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
1 file changed