[PATCH] Async IO on regular files

[Martin Wilck]

This patch implements asynchronous I/O on regular file objects.
It is against the current (02/01/02) CVS version of wine.

I know that async IO on regular files is pretty pointless at the moment,
but it's better to have it working as expected, I guess ...

The patch was successfully tested with a simple test program that checks
the sequence of scheduled reqeuests and file positioning via the
lpOverlapped->Offset and OffsetHigh fields.

server/file.c:
    struct file:		add two async_queue fields (read/write) for async IO.
    create_file_for_fd(): 	Intialize async queues.
    destroy_file(): 	destroy async queues.
    file_poll_event(): 	invoke async requests for overlapped files.
    file_queue_async(): 	implement the queue_async() method.
    file_get_info(): 	return FD_TYPE_OVERLAPPED for overlapped files.

files/file.c:
    FILE_AsyncReadService():
    	Use pread() for fd's that support seeking.
    FILE_AsyncWriteService():
    	Use pwrite() for fd's that support seeking.

Regards
Martin