[boost] [release][chrono] libs/chrono/stopwatches/include not in boost/chrono/stopwatches

Hi, In the 1.67 released archive, there is libs/chrono/stopwatches/include directory that contains headers that look like they should be placed in boost/chrono/stopwatches. With the checkout from git, `b2 headers` create links boost/chrono/stopwatches and boost/chrono/stopwatches.hpp that refer to that directory. Looks like the packaging scripts need to be updated.