How do I regain all unallocated disk space to add it to macOS after removing bootcamp partition?
OK, I managed to solve the problem and hence answer my own question.  BTW, I'm not a fan of the Disk Utility GUI version included with OS X El Capitan - too easy to commit to things without some cautionary dialogues IMO.  That being said, I was able to reformat and reclaim the missing ex-bootcamp partition by simply using Disk Utility to reduce -- yes reduce -- the size of the OS X partition slightly ~ 5GB in this case.  After waiting about 5 minutes for the changes to be completed, here is the output: