block: do not use pass uninitialized data to ReadFile()

All the others fields were uninitialized causing ReadFile() to fail.

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

src/misc/block.c

@@ -348,7 +348,7 @@ ssize_t pread (int fd, void *buf, size_t count, off_t offset)
     if (handle == INVALID_HANDLE_VALUE)
         return -1;
 
-    OVERLAPPED olap; olap.Offset = offset; olap.OffsetHigh = (offset >> 32);
+    OVERLAPPED olap = {.Offset = offset, .OffsetHigh = (offset >> 32)};
     DWORD written;
     /* This braindead API will override the file pointer even if we specify
      * an explicit read offset... So do not expect this to mix well with