Add _require_scratch_duperemove which validates that the file system
supports duperemove. This allows us to move three tests from shared/
to generic/. This means these tests will automatically adapt when
duperemove supports other file systems. Tests moved are:
shared/008 --> generic/559
shared/009 --> generic/560
shared/010 --> generic/561
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>