clipDataId is an optional field of CLIPRDR_FILECONTENTS_REQUEST.
The client should not send it to the server without sending a prior
CLIPRDR_LOCK_CLIPDATA request. The reverse is true as well: the
server should not include these additional 4 bytes without locking
the file in question.
The value zero is a valid ID, it cannot be used as a sentinel value.
Introduce a separate flag to tell whether the clipDataId has been set
and can be relied upon.
Also fix formatting. These stupid line breaks have negative impact on
readability, and the lines do fit into the 100 column limit either way.
ef4421fc77