# apply unconditional per-directory flags
define add_IS_IN_lib
ifneq ($(strip $(2)),)
-__add_IS_IN_lib := $(subst $(top_builddir),,$(2))
+__add_IS_IN_lib := $(2)
$$(__add_IS_IN_lib): CFLAGS-for-library-members:=$(CFLAGS-$(1)) -DIN_LIB=$(word 1,$(subst /, ,$(1)))
endif
endef