[boost] ]dynamic_bitset] develop change never merged to master

In going through the CMT libraries for the upcoming release I noticed a longstanding change to dynamic_bitset on the 'develop' branch that added capacity, reserve, and shrink_to_fit functionality which had never been merged to the 'master' branch. The change is purely to add functionality rather than a bug fix, but it has been tested successfully on the 'develop' branch for a long while now. Do we want this functionality in the upcoming release ? If not, this change can be merged to 'master' after the release is out for the next release.