build/win32: fix mkvenv wheel path and C++ header include order

Fix Windows build issues in both Python env setup and UI C++ headers.

- Use a plain path for pip --find-links in python/scripts/mkvenv.py instead of a file:// URL, which is unreliable on Windows paths.
- Move qemu/osdep.h outside extern "C" blocks in ui/xemu-snapshots.h and ui/xui/common.hh so C++ compilation sees expected declarations/types without C-linkage wrapping side effects.

python/scripts/mkvenv.py

@@ -683,7 +683,7 @@ def pip_install(
     if not online:
         full_args += ["--no-index"]
     if wheels_dir:
-        full_args += ["--find-links", f"file://{str(wheels_dir)}"]
+        full_args += ["--find-links", f"{wheels_dir}"]
     full_args += list(args)
     subprocess.run(
         full_args,

ui/xemu-snapshots.h

@@ -20,11 +20,12 @@
 #ifndef XEMU_SNAPSHOTS_H
 #define XEMU_SNAPSHOTS_H
 
+#include "qemu/osdep.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-#include "qemu/osdep.h"
 #include "block/snapshot.h"
 #include <epoxy/gl.h>
 

ui/xui/common.hh

@@ -31,9 +31,10 @@
 #include <misc/cpp/imgui_stdlib.h>
 #include <stb_image.h>
 
+#include "qemu/osdep.h"
+
 extern "C" {
 // Include necessary QEMU headers
-#include "qemu/osdep.h"
 #include "qapi/error.h"
 #include "system/runstate.h"
 #include "hw/xbox/mcpx/apu/apu_debug.h"