Log4CPlusCPack.cmake: Use PROJECT_SOURCE_DIR variable instead of CMAKE_SOURCE_DIR to allow using log4cplus as sub-project of another CMake project.    Suggested by: Kyle <kdawgud@users.sf.net>
Log4CPlusCPack.cmake: Use PROJECT_SOURCE_DIR variable instead of
CMAKE_SOURCE_DIR to allow using log4cplus as sub-project of another CMake
project.
  
Suggested by: Kyle <kdawgud@users.sf.net>
csuideal/log4cplus,csuideal/log4cplus,csuideal/log4cplus,hunter-packages/log4cplus,ccpaging/log4cplus,hunter-packages/log4cplus,ccpaging/log4cplus,hunter-packages/log4cplus,ccpaging/log4cplus,csuideal/log4cplus,ccpaging/log4cplus,hunter-packages/log4cplus