Fixes #5048: rudder-agent fails to build on RHEL 6 due to a missing lmdb.h file
Merge pull request #378 from jooooooon/bug_5048/rudder_agent_fails_to_build_on_rhel_6_due_to_a_missing_lmdb_h_file

Fixes #5048: rudder-agent fails to build on RHEL 6 due to a missing lmdb...