Fix lint errors in java/rocksjni/options.cc

Summary:
Fix lint errors in java/rocksjni/options.cc

Test Plan:
make rocksdbjava
Fix a check in database shutdown or Column family drop during flush.

Summary:
Fix a check in database shutdown or Column family drop during flush.

Special thanks to Maurice Barnum who spots the problem :)

Test Plan: db_test

Reviewers: ljin, igor, sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D24273
[Java] Fixed link error on library loading on Mac.

Summary:
Fixed link error on library loading on Mac.

Test Plan:
make rocksdbjava
make jtest
[Java] Fix compile error on DbBenchmark.java

Summary:
Fix compile error on DbBenchmark.java

Test Plan:
make rocksdbjava
make jdb_bench