small bug in mkfs.cramfs + patch

small bug in mkfs.cramfs + patch

mkfs.cramfs on version v2.17.2 has a small bug when dealing with very small
filesystems.  look at upstream code on git, and the issue is still here.
ex:

         $ cd /tmp
         $ mkdir content
         $ echo hello > content/a
         $ echo hello > content/b
         $ mkfs.cramfs content content.cramfs
         not enough space allocated for ROM image (4090 allocated, 4096 used)

Here is a patch for fixing (simply rounding to page size AFTER eleminating
doubles).

Signed-off-by: Arnaud Mouiche <arnaud.mouiche@invoxia.com>
Signed-off-by: Karel Zak <kzak@redhat.com>