Reverting "libdiskfs: Shutdown pagers on startup_dosync."

[Samuel Thibault]

Hello Justus,

I had to revert your commit:

“
commit f05b6bae5cbdf3c221eba05987dea7ab14e6524f
Author: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date:   Mon Jan 15 22:00:11 2018 +0100

    Revert "libdiskfs: Shutdown pagers on startup_dosync."
    
    This reverts commit 89a49ec8b3a847f3b770cff6a4a80b98b94ad7bf.
    
    There was a typo in diskfs_shutdown (FSYS_GOAWAY_FORCE || 
FSYS_GOAWAY_RECURSE)
    which was making it FSYS_GOAWAY_NOWAIT, and thus not actually syncing if
    there happens to be clients (it was then returning EBUSY). Fixing this into
    FSYS_GOAWAY_FORCE | FSYS_GOAWAY_RECURSE then makes it wait for clients (and
    NOWAIT is not supported), and there are very often some left, thus not
    syncing either.
”

I don't know if the pager actually supports the operation that we want?
(just crashing clients)

Samuel