generic/008: Add test for fallocate zero range at block boundary

generic/008: Add test for fallocate zero range at block boundary

Add test for fallocate zero range at block boundary. This is similar to
the test xfs/290 however this one is generic and we're testing different
block sizes as well - namely 1k, 2k, 4k and 64k. Note that we're not
creating file systems with given block size buy rather test all 4
options.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>