Summary:
Upstream https://salsa.debian.org/mariadb-team/mariadb-10.4/-/blob/master/debian/patches/rocksdb-kfreebsd.patch
by jrtc27.

Fixes https://github.com/facebook/rocksdb/issues/5223.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6992

Reviewed By: zhichao-cao

Differential Revision: D22084150

Pulled By: ajkr

fbshipit-source-id: 1822311ba16f112a15065b2180ce89d36af9cafc