-flags = $(foreach o,$($(1)),$(if $(filter -I%,$(o)),$(call addtree,$(o)),$(o)))
+flags = $(foreach o,$($(1)),\
+ $(if $(filter -I%,$(o)),$(call addtree,$(o)),$(o)))
+
+# echo command.
+# Short version is used, if $(quiet) equals `quiet_', otherwise full one.
+echo-cmd = $(if $($(quiet)cmd_$(1)),\
+ echo ' $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)