allow to cross-compile x86_64 kernel on Darwin

adk/include/endian.h

@@ -0,0 +1,40 @@
+#ifndef __endian_compat_h
+#define __endian_compat_h
+
+#if defined(__linux__) || defined(__CYGWIN__)
+#include <byteswap.h>
+#include_next <endian.h>
+#elif defined(__APPLE__)
+#include <machine/endian.h>
+#include <machine/byte_order.h>
+#define bswap_16(x) NXSwapShort(x)
+#define bswap_32(x) NXSwapInt(x)
+#define bswap_64(x) NXSwapLongLong(x)
+#elif defined(__FreeBSD__)
+#include <sys/endian.h>
+#define bswap_16(x) bswap16(x)
+#define bswap_32(x) bswap32(x)
+#define bswap_64(x) bswap64(x)
+#elif defined(__OpenBSD__)
+#include <sys/types.h>
+#define bswap_16(x) __swap16(x)
+#define bswap_32(x) __swap32(x)
+#define bswap_64(x) __swap64(x)
+#else
+#include <machine/endian.h>
+#define bswap_16(x) swap16(x)
+#define bswap_32(x) swap32(x)
+#define bswap_64(x) swap64(x)
+#endif
+
+#ifndef __BYTE_ORDER
+#define __BYTE_ORDER BYTE_ORDER
+#endif
+#ifndef __BIG_ENDIAN
+#define __BIG_ENDIAN BIG_ENDIAN
+#endif
+#ifndef __LITTLE_ENDIAN
+#define __LITTLE_ENDIAN LITTLE_ENDIAN
+#endif
+
+#endif

mk/kernel-vars.mk

@@ -18,7 +18,7 @@ endif
 # non-Linux platforms need elf.h
 ifneq ($(OS_FOR_BUILD),Linux)
 KERNEL_MAKE_OPTS+=	HOSTCFLAGS='$(HOST_CPPFLAGS) ${HOST_CFLAGS}'
-KERNEL_MAKE_OPTS+=	HOST_EXTRACFLAGS='-I${ADK_TOPDIR}/adk/include -DKBUILD_NO_NLS'
+KERNEL_MAKE_OPTS+=	HOST_EXTRACFLAGS='-I${LINUX_DIR}/tools/include -I${ADK_TOPDIR}/adk/include -DKBUILD_NO_NLS'
 else
 KERNEL_MAKE_OPTS+=	HOSTCFLAGS='${HOST_CFLAGS}'
 endif