Summary:
In #4652 we are setting -Os for lite builds only when LITE=1 is specified. But currently almost all the users invoke lite build via OPT="-DROCKSDB_LITE=1". So this diff tries to set LITE=1 when users already pass in -DROCKSDB_LITE=1 via the command line.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4671

Differential Revision: D13033801

Pulled By: sagar0

fbshipit-source-id: e7b506cee574f9e3f42221ee6647915011c78d78