anv,iris: work around missing <linux/sync_file.h> on BSDs
Regressed by 812cf5f5 and abf8aed6. Neither DragonFly, nor FreeBSD, nor NetBSD install <linux/sync_file.h>
. However, OpenBSD probably does. CC @manu
../src/intel/vulkan/anv_gem.c:31:10: fatal error: 'linux/sync_file.h' file not found
#include <linux/sync_file.h>
^~~~~~~~~~~~~~~~~~~
../src/gallium/drivers/iris/iris_fence.c:29:10: fatal error: 'linux/sync_file.h' file not found
#include <linux/sync_file.h>
^~~~~~~~~~~~~~~~~~~
https://github.com/openbsd/src/blob/68a1d3c69b86/sys/dev/pci/drm/include/linux/sync_file.h https://github.com/openbsd/src/blob/68a1d3c69b86/include/Makefile#L124-L129