Rename _scratch_mount to _scratch_cycle_mount

This makes it clear when we are using "mount ; umount" versus "mount
-o remount" for most file systems.  The reason for this distinction is
(a) tests may want to test the difference between what happens on the
remount versus the munt paths, (b) with tmpfs, "mount ; umount" will
cause the contents of all of the files to disappear which makes many
tests sad, and (c) some mount options may not be changed using "mount
-o remount".

Currently _scratch_mount performs "_scratch_mount ; _scratch_umount"
so mechnically rename this function to _scratch_cycle_mount.  This was
done mechnically using the script fragment:

git grep "_scratch_remount" | \
	awk -F: '{print $1}' | sort -u | \
	xargs sed -i 's/_scratch_remount/_scratch_cycle_mount/g'

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

tests/btrfs/052

@@ -149,7 +149,7 @@ test_btrfs_clone_same_file()
 	# Check that after defragmenting the file and re-mounting, the file
 	# content remains exactly the same as before.
 	_run_btrfs_util_prog filesystem defragment $SCRATCH_MNT/foo
-	_scratch_remount
+	_scratch_cycle_mount
 	od -t x1 $SCRATCH_MNT/foo | _filter_od
 
 	# Verify that there are no consistency errors.