add conex_random.cpp to cxroot via CMake target_sources()

modules/conex/CMakeLists.txt

 add_subdirectory(cxroot)
 
-add_library(conex_random STATIC conex_random.cpp)
-target_link_libraries(conex_random PUBLIC modules_common)
-target_link_libraries(CONEXsibyll conex_random)
-
-#
-# add to combined CORSIKA8 target
-#
-add_dependencies (CORSIKA8 CONEXsibyll)
-target_link_libraries (CORSIKA8 INTERFACE CONEXsibyll)
-
-#
-# install and export
-#  
-install (
-  TARGETS CONEXsibyll conex_random
-  EXPORT CORSIKA8PublicTargets
-  ARCHIVE DESTINATION lib/corsika
-  PUBLIC_HEADER DESTINATION include/corsika_modules/conex
-  )
+target_sources(CONEXsibyll PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/conex_random.cpp)