Fix block example again. Refs #8545.

git-svn-id: http://svn.boost.org/svn/boost/trunk@84175 b8fc166d-592f-0410-95f2-cb63ce0dd405
Fixed incorrect target buffer alignment and filling.

git-svn-id: http://svn.boost.org/svn/boost/trunk@84176 b8fc166d-592f-0410-95f2-cb63ce0dd405
Resolved signed/unsigned comparison mismatch.

git-svn-id: http://svn.boost.org/svn/boost/trunk@84177 b8fc166d-592f-0410-95f2-cb63ce0dd405
Fixed syntax error.

git-svn-id: http://svn.boost.org/svn/boost/trunk@84178 b8fc166d-592f-0410-95f2-cb63ce0dd405