when client disconnects, timeout all pending clipboard requests

[Antoine Martin]

Instead we see:

Warning: remote clipboard request timed out
 request id 4, selection=PRIMARY, target=TIMESTAMP
Warning: remote clipboard request timed out
 request id 5, selection=PRIMARY, target=TARGETS
Warning: remote clipboard request timed out
 request id 6, selection=PRIMARY, target=text/html
Warning: remote clipboard request timed out
 request id 7, selection=PRIMARY, target=image/bmp
Warning: remote clipboard request timed out
 request id 8, selection=PRIMARY, target=text/plain;charset=UTF-8
Warning: remote clipboard request timed out
 request id 9, selection=PRIMARY, target=UTF8_STRING
Warning: remote clipboard request timed out
 request id 10, selection=PRIMARY, target=text/plain;charset=ISO-10646-UCS-2
Warning: remote clipboard request timed out
 request id 11, selection=PRIMARY, target=text/unicode
Warning: remote clipboard request timed out
 request id 12, selection=PRIMARY, target=text/plain
Warning: remote clipboard request timed out
 request id 13, selection=PRIMARY, target=STRING

[Antoine Martin]

Fixed in r25615.