Summary:
We have replaced LEVELDB_PLATFORM_POSIX with ROCKSDB_PLATFORM_POSIX in our code
replace it in Makefile
Test Plan: make check
Reviewers: sdong, yiwu, andrewkr, lightmark
Reviewed By: lightmark
Subscribers: andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D61365