If a file is deleted while a brick is offline, and a file by the same
name is subsequently created once the brick has been brought back
online but not fully healed, the brick returns the old, pre-deletion
GFID for the file, This results in lack of consensus about the GFID,
which is bad, and usually manifests as EROFS.

Fix by making bricks honor the GFID requested by the server when
a file is created, even if there is a pre-existing one. This fixes
the race and has the additional benefit that any clients with the old
GFID will get ESTALE accessing the old file instead of silently
getting access to a file which differs fromthe one they thought they
were accessing.