This is xnu-8019. See this file in:
export MakeInc_cmd=${SRCROOT}/makedefs/MakeInc.cmd
export MakeInc_def=${SRCROOT}/makedefs/MakeInc.def
export MakeInc_rule=${SRCROOT}/makedefs/MakeInc.rule
export MakeInc_dir=${SRCROOT}/makedefs/MakeInc.dir

include $(MakeInc_cmd)
include $(MakeInc_def)

INSTINC_SUBDIRS =

INSTINC_SUBDIRS_X86_64 =	\
	i386

INSTINC_SUBDIRS_X86_64H =	\
	i386

INSTINC_SUBDIRS_ARM =	\
	arm

INSTINC_SUBDIRS_ARM64 =	\
	arm

EXPORT_FILES =

INSTALL_MI_LIST =

INSTALL_MI_DIR = architecture

INSTALL_KF_MI_LIST = byte_order.h

EXPORT_MI_LIST = ${EXPORT_FILES}

EXPORT_MI_DIR = architecture

include $(MakeInc_rule)
include $(MakeInc_dir)