Recursion Make
https://www.gnu.org/software/make/manual/make.html#Recursion
subdirs: $(patsubst %, _dir_%, $(DIRS))
$(patsubst %, _dir_%, $(DIRS)): headers
$(MAKE) -C $(patsubst _dir_%, %, $@)
https://www.gnu.org/software/make/manual/make.html#Recursion
subdirs: $(patsubst %, _dir_%, $(DIRS))
$(patsubst %, _dir_%, $(DIRS)): headers
$(MAKE) -C $(patsubst _dir_%, %, $@)