Currently CMakeLists doesn't look for LMDB, a required dependency
for sink. This commit creates a FindLMDB script based in an original
script available in BSD license and add it to CMakeLists.txt.

Remove LMDB development library and try to compile sink. The CMake
process will end with success but in compilation time you will get
the follow error message sink/common/storage_lmdb.cpp:35:18: fatal
error: lmdb.h: Arquivo ou diretório não encontrado compilation terminated.

After apply the patch, the look for LMDB will work and the CMake
process will fail because there is not LMDB installed.

So, just install LMDB development and the CMake process will find
the library and the process will end successfully.