gh01 - h2_leveldb_impl_drv.cc doesn't compile under Erlang/OTP 17.5
gh01 - h2_leveldb_impl_drv.cc doesn't compile under Erlang/OTP 17.5

Add 'emergency_close' to ErlDrvEntry.

marksteele/h2leveldb,leveldb-erlang/h2leveldb,marksteele/h2leveldb,leveldb-erlang/h2leveldb,leveldb-erlang/h2leveldb,marksteele/h2leveldb