message: Fix Error Message (although build logic was correct already): Running Linux does not automatically mean that X11 is missing
diff: @@ -107,14 +107,16 @@ target_link_libraries(${MODULE} ${LIBDEPS})
  set_target_properties(${MODULE} PROPERTIES COMPILE_FLAGS "")
  # System dependent: Modify the way the library is build
  -if(${CMAKE_SYSTEM} MATCHES Darwin AND X11_FOUND)
  +if(${CMAKE_SYSTEM} MATCHES Darwin)
  + if (X11_FOUND)
  set_target_properties(${MODULE} PROPERTIES LINK_FLAGS "-undefined dynamic_lookup")
  include_directories(${X11_INCLUDE_DIR})
  SET(CMAKE_EXE_LINKER_FLAGS
  "${CMAKE_EXE_LINKER_FLAGS} -L${X11_LIB_DIR}")
  else()
  message(WARNING "X11 libraries not found - will NOT build ZMQhistViewer")
  -endif(${CMAKE_SYSTEM} MATCHES Darwin AND X11_FOUND)
  + endif(X11_FOUND)
  +endif(${CMAKE_SYSTEM} MATCHES Darwin)
  # Installation
  install(TARGETS ${MODULE}
  