Fix lint-002-build-dir-handling

Fix lint-002-build-dir-handling

That lint test requires some Kconfig defaults and uses allyesconfig
for that. Unfortunately that also draws in ccache and scanbuild support,
which significantly change the behaviour of the toplevel Makefile.
Notably, the ccache support breaks if no ccache is installed.

Change-Id: I17cbb7974be33fc077e5cbd5fb616a5b00a47d97
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: http://review.coreboot.org/80
Tested-by: build bot (Jenkins)