Summary:
Before the fix:
On a PowerPC machine, run the following
```
$ make jtest
```
The command will fail due to "undefined symbol: crc32c_ppc". It was caused by
'rocksdbjava' Makefile target not including crc32c_ppc object files when
generating the shared lib. The fix is simple.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4357

Differential Revision: D9779474

Pulled By: riversand963

fbshipit-source-id: 3c5ec9068c2b9c796e6500f71cd900267064fd51