common/buffer: fix SIGABRT in rebuild_aligned_size_and_memory

common/buffer: fix SIGABRT in  rebuild_aligned_size_and_memory

There is such a bl, which needs to satisfy two conditions:
1)all ptrs' length sum except last ptr is aligned with 4K;
2)the length of last ptr is 0.
This bl will cause stack corruption when calling
bufferlist::rebuild_aligned_size_and_memory().

Deal with this special scenario in rebuild_aligned_size_and_memory() to
solve the bug. And added a specialtest-case to reproduce this scenario.

Fixes: https://tracker.ceph.com/issues/51419
Signed-off-by: Yin Congmin <congmin.yin@intel.com>