option to disable navgent

Makefile

@@ -177,6 +177,9 @@ maps/%.bsp: %.bsp
 	rm -i "$(MOD_DIR)/mapsrc/setphys.vmf"
 
 %.nav: %.bsp
+ifeq ($(NAV),0)
+	echo "user disabled nav gen via NAV=0"
+else
 	rm -v "$(MOD_DIR)/maps/navgen.bsp" || true
 	cp -v "$^" "$(MOD_DIR)/maps/navgen.bsp"
 	mkdir -p "$(MOD_DIR)/data/"
@@ -197,6 +200,7 @@ maps/%.bsp: %.bsp
 	mkdir -p maps/graphs
 	cp -v "$(MOD_DIR)/maps/graphs/navgen.ain" $(basename $@).ain
 	rm -v "$(MOD_DIR)/maps/graphs/navgen.ain"
+endif
 
 
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