ENHANCED: threads/0, join_threads/0: use print_message/2.  Output of threads now includes time and stack usage.
ENHANCED: threads/0, join_threads/0: use print_message/2.  Output of
threads now includes time and stack usage.

mndrix/swipl-devel,jn7163/swipl-devel,jn7163/swipl-devel,koryonik/swipl-devel,edechter/swipl-devel,mndrix/swipl-devel,mndrix/swipl-devel,jn7163/swipl-devel,edechter/swipl-devel,koryonik/swipl-devel,edechter/swipl-devel,jn7163/swipl-devel,koryonik/swipl-devel,jn7163/swipl-devel,koryonik/swipl-devel,mndrix/swipl-devel,mndrix/swipl-devel,edechter/swipl-devel,koryonik/swipl-devel,edechter/swipl-devel