title: How to link google protobuf libraries via cmake on linux?
body: <p>I'm trying to make it same way I made it for boost :</p>
  
  <pre><code>find_package(Boost COMPONENTS system filesystem REQUIRED)                                                    
  find_package(ProtocolBuffers)                                                                                
  
  ## Compiler flags                                                                                            
  if(CMAKE_COMPILER_IS_GNUCXX)                                                                                 
      set(CMAKE_CXX_FLAGS "-O2")                                                                               
      set(CMAKE_EXE_LINKER_FLAGS "-lsqlite3 -lrt -lpthread")                                                   
  endif()                                                                                                      
  
  target_link_libraries(complex                                                                                
    ${Boost_FILESYSTEM_LIBRARY}                                                                                
    ${Boost_SYSTEM_LIBRARY}                                                                                    
    ${PROTOBUF_LIBRARY}                                                                                        
  )  
  </code></pre>
  
  <p>(googled it somewhere) but got bad output:</p>
  
  <pre><code>CMake Warning at complex/CMakeLists.txt:18 (find_package):
    Could not find module FindProtocolBuffers.cmake or a configuration file for
    package ProtocolBuffers.
  
    Adjust CMAKE_MODULE_PATH to find FindProtocolBuffers.cmake or set
    ProtocolBuffers_DIR to the directory containing a CMake configuration file
    for ProtocolBuffers.  The file will have one of the following names:
  
      ProtocolBuffersConfig.cmake
      protocolbuffers-config.cmake
  </code></pre>
  
  <p>How can I link it with cmake? or maybe I even can compile .proto file using cmake?</p>