FIXED: current_atom/1 could return a garbage-collected atom if another thread runs AGC.
FIXED: current_atom/1 could return a garbage-collected atom if another thread
runs AGC.

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