what-jenkins-does: Adapt to recent libpayload kconfig changes

Since we don't actually use this target at this time, it was bitrotting.
Fix it up, so we can start to use it.

Change-Id: I27d2ed4fb2640680acf739a87d61cb0d1463d705
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: http://review.coreboot.org/11095
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
diff --git a/Makefile.inc b/Makefile.inc
index 14fa990..2a4eaf6 100644
--- a/Makefile.inc
+++ b/Makefile.inc
@@ -683,5 +683,5 @@
 	util/abuild/abuild -B -J $(if $(JENKINS_NOCCACHE),,-y) -c 4 -z -p $(JENKINS_PAYLOAD)
-	(cd payloads/libpayload; $(MAKE) $(if $(JENKINS_NOCCACHE),,CONFIG_CCACHE=y) V=$(V) Q=$(Q) junit.xml)
+	(cd payloads/libpayload; unset COREBOOT_BUILD_DIR; $(MAKE) $(if $(JENKINS_NOCCACHE),,CONFIG_LP_CCACHE=y) V=$(V) Q=$(Q) junit.xml)
 	$(MAKE) V=$(V) Q=$(Q) -C util/cbmem junit.xml