Simplify DetectBuildSystemConflict CMake utility

endfunction(GenerateStyleHeaders)

function(DetectBuildSystemConflict lammps_src_dir)

  math(EXPR N "${ARGC}-1")

  if(N GREATER 0)

    math(EXPR ARG_END   "${ARGC}-1")

    foreach(IDX RANGE 1 ${ARG_END})

        list(GET ARGV ${IDX} SRC_FILE)

  if(ARGC GREATER 1)

    list(REMOVE_AT ARGV 0)

    foreach(SRC_FILE ${ARGV})

        get_filename_component(FILENAME ${SRC_FILE} NAME)

        if(EXISTS ${lammps_src_dir}/${FILENAME})

            message(FATAL_ERROR "\n########################################################################\n"