Summary:
Add the jni library for musl-libc, specifically for incorporating into Alpine based docker images. The classifier is `musl64`.
I have signed the CLA electronically.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/3143
Differential Revision: D18719372
fbshipit-source-id: 6189d149310b6436d6def7d808566b0234b23313
