package/xen: Include linux/limits.h when building QEMU inside of Xen

If building Xen and not using glibc (using musl for example) the QEMU
project inside of Xen fails to build as it relys on the XATTR_SIZE_MAX
macro which is defined in <linux/limits.h>.

Glibc includes this header indirectly but as that is not part of the
POSIX standard other libraries don't neccessearily have this. To fix the
issue we explicitly include <linux/limits.h> to ensure the build works
for all libc libraries.

Fixes:
  http://autobuild.buildroot.net/results/bb1/bb1310eb1464d880a357ae5e491fd168361d25a0

Signed-off-by: Alistair Francis <alistair.francis@xilinx.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/xen/0002-9pfs-include-linux-limits.h-for-XATTR_SIZE_MAX.patch

@@ -0,0 +1,43 @@
+Message-Id: <07010a2ad79559c412949f0005dbe3cb03d8416e.1498504812.git.ps@pks.im>
+From: Patrick Steinhardt <ps@pks.im>
+Date: Mon, 26 Jun 2017 21:20:45 +0200
+Subject: [PATCH] 9pfs: include <linux/limits.h> for XATTR_SIZE_MAX
+
+The function `v9fs_xattrcreate` makes use of the define `XATTR_SIZE_MAX`
+to reject attempts of creating xattrs with an invalid size, which is
+defined in <linux/limits.h>. On glibc-based systems, this header is
+indirectly included via <limits.h>, <bits/posix1_lim.h>,
+<bitts/local_lim.h>, but on other platforms this is not guaranteed due
+to not being part of the POSIX standard. One examples are systems based
+on musl libc, which do not include the <linux/limits.h> indirectly,
+which leads to `XATTR_SIZE_MAX` being undefined.
+
+Fix this error by directly include <linux/limits.h>. As the 9P fs code
+is being Linux-based either way, we can simply do so without breaking
+other platforms. This enables building 9pfs on musl-based systems.
+
+Signed-off-by: Patrick Steinhardt <ps@pks.im>
+[ Changes by AF
+ - Apply to the QEMU tree inside of Xen
+]
+Signed-off-by: Alistair Francis <alistair.francis@xilinx.com>
+---
+Upstream Status: Pending review and acceptance
+
+ tools/qemu-xen/hw/9pfs/9p.c | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/tools/qemu-xen/hw/9pfs/9p.c b/tools/qemu-xen/hw/9pfs/9p.c
+index 96d2683348..48cd558e96 100644
+--- a/tools/qemu-xen/hw/9pfs/9p.c
++++ b/tools/qemu-xen/hw/9pfs/9p.c
+@@ -13,6 +13,7 @@
+ 
+ #include "qemu/osdep.h"
+ #include <glib/gprintf.h>
++#include <linux/limits.h>
+ #include "hw/virtio/virtio.h"
+ #include "qapi/error.h"
+ #include "qemu/error-report.h"
+-- 
+2.13.2