btrfs: check that cloning an inline extent does not lead to data loss

btrfs: check that cloning an inline extent does not lead to data loss

We have a bug in the current kernel merge window (for 5.7) that results
in data loss when cloning an inline extent into a new file (or an empty
file. This change adds a test for such case into the existing test case
btrfs/205, because it's the test case that tests all the supported
scenarios for cloning inline extents in btrfs.

Linux kernel commit 4fdb688c7071 ("btrfs: fix lost i_size update
after cloning inline extent") fixes the regression.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>