Fix zstd/zdict include path for java static build

Fix zstd/zdict include path for java static build

Summary:
With the ZSTD dictionary generator support added in #3057
`PORTABLE=1 ROCKSDB_NO_FBCODE=1 make rocksdbjavastatic` fails as it can't find zdict.h. Specifically due to:
https://github.com/facebook/rocksdb/blob/e3a06f12d27fd50af7b6c5941973f529601f9a3e/util/compression.h#L39
In java static builds zstd code gets directly downloaded from https://github.com/facebook/zstd , and in there zdict.h is under dictBuilder directory. So, I modified libzstd.a target to use `make install` to collect all the header files into a single location and used that as the zstd's include path.
Closes https://github.com/facebook/rocksdb/pull/3260

Differential Revision: D6669850

Pulled By: sagar0

fbshipit-source-id: f8a7562a670e5aed4c4fb6034a921697590d7285