Log Message:
Update databases/mongo-c-driver to 1.8.2.

- Remove option to bundle the Snappy compression library, it caused issues
  for programs linking to libmongoc
- Fix pkg-config and CMake config file flags for programs that statically
  link to libmongoc when libmongoc is statically linked to zLib
- The configure flag "--with-zlib=no" was ignored
- Fix crash in authentication when username is NULL