[Not for commit] clang-format examples

Summary: Just for discussion

Test Plan: N/A

Reviewers: sdong, igor, haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D15057
Separate the aligned and unaligned memory allocation

Summary: Use two vectors for different types of memory allocation.

Test Plan: run all unit tests.

Reviewers: haobo, sdong

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D15027