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 = pexpert
INSTINC_SUBDIRS_X86_64 = pexpert
INSTINC_SUBDIRS_X86_64H = pexpert
INSTINC_SUBDIRS_ARM = pexpert
INSTINC_SUBDIRS_ARM64 = pexpert


EXPINC_SUBDIRS = pexpert
EXPINC_SUBDIRS_X86_64 = pexpert
EXPINC_SUBDIRS_X86_64H = pexpert
EXPINC_SUBDIRS_ARM = pexpert
EXPINC_SUBDIRS_ARM64 = pexpert

COMP_SUBDIRS =	\
	conf

include $(MakeInc_rule)
include $(MakeInc_dir)