# Make version check
REQUIRED_MAKE_VERSION:=3.81
ifneq ($(shell ( echo "$(MAKE_VERSION)" ; echo "$(REQUIRED_MAKE_VERSION)" ) | sort -t. -n | head -1),$(REQUIRED_MAKE_VERSION))
ifneq "$(REQUIRED_MAKE_VERSION)" "$(firstword $(sort $(REQUIRED_MAKE_VERSION) $(MAKE_VERSION)))"
$(error GNU make version $(REQUIRED_MAKE_VERSION) required)
endif