makefile: defined but empty variables are now included in make issue

fixes #1166

Signed-off-by: Øyvind Harboe <[email protected]>

Author: oharboe

flow/util/utils.mk

@@ -85,7 +85,7 @@ define \n
 
 endef
 
-export ISSUE_VARIABLES := $(foreach V, $(.VARIABLES),$(if $(filter-out environment% default automatic, $(origin $V)), $(if $(filter-out .% %QT_QPA_PLATFORM% %TIME_CMD% KLAYOUT% GENERATE_ABSTRACT_RULE%, $(V)),$V=$($V))${\n}))
+export ISSUE_VARIABLES := $(foreach V, $(.VARIABLES),$(if $(filter-out environment% default automatic, $(origin $V)), $(if $(filter-out .% %QT_QPA_PLATFORM% %TIME_CMD% KLAYOUT% GENERATE_ABSTRACT_RULE%, $(V)), $(if $($V),$V=$($V),$V=''))${\n}))
 
 $(foreach script,$(ISSUE_SCRIPTS),$(script)_issue): %_issue : versions.txt
 	$(UTILS_DIR)/makeIssue.sh $*