[U-Boot] idirafter causes host sha256.h to be included

Hello,

tools/Makefile uses the following substitution

HOST_EXTRACFLAGS += -include $(srctree)/include/libfdt_env.h \ $(patsubst -I%,-idirafter%, $(UBOOTINCLUDE)) \ ...

Which adds -idirafterinclude when compiling image-fit.c. Since mentioned file includes sha256.h, which is a system include on FreeBSD, the system version is included instead of the intended U-boot include/sha256.h and building fails. Without the substitution it builds successfully.

What is the intention of using idirafter?

Regards, Jeroen