Summary:
`${TESTUTILLIB}` should be linked with targets`${LIBS}`, otherwise it may not find the references. After that, we have to work fine with `${CMAKE_CURRENT_SOURCE_DIR}` in `cmake/modules/ReadVersion.cmake`, while building external projects with `add_subdirectory(/path/to/rocksdb)`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6045
Differential Revision: D18641791
Pulled By: pdillinger
fbshipit-source-id: a56b03b4dda6bae6edce1375324f51340917dddc
suzanwen