shared/005: Test multiple fallocate collapse

shared/005: Test multiple fallocate collapse

We execute collapse range multiple times on same file.  Each
collapse range call collapses a single alternate block.  After the
test execution, file will be left with 80 blocks and as much number
of extents.  We also check for file system consistency after the
completion.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Ashish Sangwan <a.sangwan@samsung.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>