Remove MAX_SESS_ENTRIES and MAX_CONN_ENTRIES limits

Remove MAX_SESS_ENTRIES and MAX_CONN_ENTRIES limits
as they are no longer needed now we have IDL marshalling.
Change the calculation of the 32-bit fileid we return
to a Windows client. We can't just use the generation
count as it starts at zero for every smbd - and this
command must enumerate all files open across all smbds.
We'd really like combination of process-id + dev + inode +
generation count to be unique, but as we can't fit that
into 32 bits just use 16 bits of pid + generation count.
Jeremy.