Support fallocate(2) modes on FUSE

I39f7f69bb615977b8a8e7c84368ed043cdaf7665 added fallocate(2) support
for FUSE conservatively. It was implemented with posix_fallocate(3)
which only supports the default '0' mode in fallocate(2)

Now, we support other modes

Bug: 184920848
Test: Manual
Change-Id: I5965c607a3225fd3b23dc7a41229494d3914c3db
1 file changed