Start each run of CustomTarget_odk/build-examples with a clean slate

Change-Id: Icf6a12254b32c6fcdb7e9cbe1057c73907cf3005
Reviewed-on: https://gerrit.libreoffice.org/49860Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

odk/CustomTarget_build-examples.mk

@@ -93,6 +93,7 @@ ifneq ($(gb_SUPPRESS_TESTS),)
 	@true
 else
 	$(call gb_Output_announce,$(subst $(WORKDIR)/,,$@),$(true),CHK,1)
+	rm -fr $(call gb_CustomTarget_get_workdir,odk/build-examples)/{out,user}
 ifeq (MACOSX,$(OS))
 	$(eval ODK_BUILD_SHELL := $(shell $(gb_MKTEMP)))
 	cp /bin/sh "$(ODK_BUILD_SHELL)"