block/nfs: Fix 32-bit Windows build

libnfs.h declares nfs_fstat() as the following for win32:

  int nfs_fstat(struct nfs_context *nfs, struct nfsfh *nfsfh,
                struct __stat64 *st);

The 'st' parameter should be of type 'struct __stat64'. The
codes happen to build successfully for 64-bit Windows, but it
does not build for 32-bit Windows.

Fixes: 6542aa9 ("block: add native support for NFS")
Fixes: 18a8056 ("block/nfs: cache allocated filesize for read-only files")
Signed-off-by: Bin Meng <bin.meng@windriver.com>
Message-Id: <20220908132817.1831008-6-bmeng.cn@gmail.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/nfs.c

@@ -418,7 +418,11 @@ static int64_t nfs_client_open(NFSClient *client, BlockdevOptionsNfs *opts,
                                int flags, int open_flags, Error **errp)
 {
     int64_t ret = -EINVAL;
+#ifdef _WIN32
+    struct __stat64 st;
+#else
     struct stat st;
+#endif
     char *file = NULL, *strp = NULL;
 
     qemu_mutex_init(&client->mutex);
@@ -781,7 +785,11 @@ static int nfs_reopen_prepare(BDRVReopenState *state,
                               BlockReopenQueue *queue, Error **errp)
 {
     NFSClient *client = state->bs->opaque;
+#ifdef _WIN32
+    struct __stat64 st;
+#else
     struct stat st;
+#endif
     int ret = 0;
 
     if (state->flags & BDRV_O_RDWR && bdrv_is_read_only(state->bs)) {