kernel: generic: fix MIPS build on non-linux hosts

calc_vmlinuz_load_addr.c requires SZ_64K to be defined for alignment
purposes.  It included "../../../../include/linux/sizes.h" to define
that size, however "sizes.h" tries to include <linux/const.h> which
assumes linux system headers.  These may not exist eg. the following
error was encountered when building Linux for OpenWrt under macOS:

In file included from arch/mips/boot/compressed/calc_vmlinuz_load_addr.c:16:
arch/mips/boot/compressed/../../../../include/linux/sizes.h:11:10: fatal error: 'linux/const.h' file not found

Change makefile to force building on local linux headers instead of
system headers.  Also change eye-watering relative reference in include
file spec.

Thanks to Jo-Philip Wich & Petr Štetiar for assistance in tracking this
down & fixing.

Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>

target/linux/generic/pending-4.19/100-MIPS-fix-build-on-non-linux-hosts.patch

@@ -0,0 +1,62 @@
+From 4ee213d8c2afeab9a68f8530317260298b4b6b82 Mon Sep 17 00:00:00 2001
+From: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
+Date: Wed, 19 Jun 2019 08:16:33 +0100
+Subject: [PATCH] MIPS: fix build on non-linux hosts
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+calc_vmlinuz_load_addr.c requires SZ_64K to be defined for alignment
+purposes.  It included "../../../../include/linux/sizes.h" to define
+that size, however "sizes.h" tries to include <linux/const.h> which
+assumes linux system headers.  These may not exist eg. the following
+error was encountered when building Linux for OpenWrt under macOS:
+
+In file included from arch/mips/boot/compressed/calc_vmlinuz_load_addr.c:16:
+arch/mips/boot/compressed/../../../../include/linux/sizes.h:11:10: fatal error: 'linux/const.h' file not found
+         ^~~~~~~~~~
+
+Change makefile to force building on local linux headers instead of
+system headers.  Also change eye-watering relative reference in include
+file spec.
+
+Thanks to Jo-Philip Wich & Petr Štetiar for assistance in tracking this
+down & fixing.
+
+Suggested-by: Jo-Philipp Wich <jo@mein.io>
+Signed-off-by: Petr Štetiar <ynezz@true.cz>
+Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
+---
+ arch/mips/boot/compressed/Makefile                 | 2 ++
+ arch/mips/boot/compressed/calc_vmlinuz_load_addr.c | 2 +-
+ 2 files changed, 3 insertions(+), 1 deletion(-)
+
+diff --git a/arch/mips/boot/compressed/Makefile b/arch/mips/boot/compressed/Makefile
+index 3c453a1f1ff1..172801ed35b8 100644
+--- a/arch/mips/boot/compressed/Makefile
++++ b/arch/mips/boot/compressed/Makefile
+@@ -78,6 +78,8 @@ OBJCOPYFLAGS_piggy.o := --add-section=.image=$(obj)/vmlinux.bin.z \
+ $(obj)/piggy.o: $(obj)/dummy.o $(obj)/vmlinux.bin.z FORCE
+ 	$(call if_changed,objcopy)
+ 
++HOSTCFLAGS_calc_vmlinuz_load_addr.o += $(LINUXINCLUDE)
++
+ # Calculate the load address of the compressed kernel image
+ hostprogs-y := calc_vmlinuz_load_addr
+ 
+diff --git a/arch/mips/boot/compressed/calc_vmlinuz_load_addr.c b/arch/mips/boot/compressed/calc_vmlinuz_load_addr.c
+index 240f1d12df75..080b926d2623 100644
+--- a/arch/mips/boot/compressed/calc_vmlinuz_load_addr.c
++++ b/arch/mips/boot/compressed/calc_vmlinuz_load_addr.c
+@@ -9,7 +9,7 @@
+ #include <stdint.h>
+ #include <stdio.h>
+ #include <stdlib.h>
+-#include "../../../../include/linux/sizes.h"
++#include <linux/sizes.h>
+ 
+ int main(int argc, char *argv[])
+ {
+-- 
+2.20.1 (Apple Git-117)
+