Updating submodules
Summary:
GitHub commits:
https://github.com/facebook/rocksdb/commit/18cf0de64085b74388ba4df029ea8d7c83ec428d
https://github.com/pytorch/fbgemm/commit/df3425807f977fda0eddd5e2396b6f4556d2fecd
Test Plan: n/a
Reviewed By: yns88
fbshipit-source-id: 52fb08a9119c9e2933e735cf3415f681070292cc
