venus: Guard Linux-specific code against being compiled on Windows

v2:
- drop most additions except thread id
- fix DRM_FORMAT_MOD_LINEAR in a different way

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/38969>

src/virtio/vulkan/vn_common.h

@@ -20,16 +20,13 @@
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
-#include <sys/syscall.h>
 #include <vulkan/vulkan.h>
 
 #include "c11/threads.h"
-#include "drm-uapi/drm_fourcc.h"
 #include "util/bitscan.h"
 #include "util/bitset.h"
 #include "util/compiler.h"
 #include "util/detect_os.h"
-#include "util/libsync.h"
 #include "util/list.h"
 #include "util/macros.h"
 #include "util/os_time.h"
@@ -51,6 +48,15 @@
 #include "vk_queue.h"
 #include "vk_util.h"
 
+#if DETECT_OS_WINDOWS
+#include <processthreadsapi.h>
+#else
+#include <sys/syscall.h>
+
+#include "drm-uapi/drm_fourcc.h"
+#include "util/libsync.h"
+#endif
+
 #include "vn_entrypoints.h"
 
 #define VN_DEFAULT_ALIGN             8
@@ -614,8 +620,10 @@ vn_gettid(void)
 {
 #if DETECT_OS_ANDROID
    return gettid();
-#elif defined(__FreeBSD__)
+#elif DETECT_OS_FREEBSD
    return syscall(SYS_thr_self);
+#elif DETECT_OS_WINDOWS
+   return GetCurrentThreadId();
 #else
    return syscall(SYS_gettid);
 #endif

src/virtio/vulkan/vn_wsi.c

@@ -19,6 +19,10 @@
 #include "vn_physical_device.h"
 #include "vn_queue.h"
 
+#ifndef DRM_FORMAT_MOD_LINEAR
+#define DRM_FORMAT_MOD_LINEAR 0
+#endif
+
 /* The common WSI support makes some assumptions about the driver.
  *
  * In wsi_device_init, it assumes VK_EXT_pci_bus_info is available.  In