vfs_default: Use openat2(RESOLVE_NO_SYMLINKS) if available

vfs_default: Use openat2(RESOLVE_NO_SYMLINKS) if available

This improves the following test:

 time smbtorture //127.0.0.1/m -Uroot%test \
        smb2.create.bench-path-contention-shared \
        --option='torture:bench_path=Apps\1\2\3\4\5\6\7\8\9\10' \
        --option="torture:timelimit=600" \
        --option="torture:nprocs=1"

From:

   open[num/s=14186,avslat=0.000044,minlat=0.000042,maxlat=0.000079]
   close[num/s=14185,avslat=0.000027,minlat=0.000025,maxlat=0.000057]

to:

   open[num/s=16917,avslat=0.000038,minlat=0.000035,maxlat=0.000340]
   close[num/s=16916,avslat=0.000020,minlat=0.000019,maxlat=0.000104]

Pair-Programmed-With: Stefan Metzmacher <metze@samba.org>

Signed-off-by: Volker Lendecke <vl@samba.org>
Signed-off-by: Stefan Metzmacher <metze@samba.org>