generic: test for atime-related mount options

Tests the noatime, relatime, strictatime and nodiratime mount
options.

There is an extra check for Btrfs to ensure that the access time is
never updated on read-only subvolumes. (Regression test for bug
fixed with commit 93fd63c2f001ca6797c6b15b696a484b165b4800)

Signed-off-by: Koen De Wit <koen.de.wit@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

common/rc

@@ -2159,6 +2159,14 @@ _verify_reflink()
                || echo "$1 and $2 are not reflinks: different extents"
 }
 
+_require_relatime()
+{
+        _scratch_mkfs > /dev/null 2>&1
+        _mount -t $FSTYP -o relatime $SCRATCH_DEV $SCRATCH_MNT || \
+                _notrun "relatime not supported by the current kernel"
+	_scratch_unmount
+}
+
 _create_loop_device()
 {
 	file=$1