Added a workaround for MSVC that allows to prevent conversion to void*.

git-svn-id: http://svn.boost.org/svn/boost/trunk@84116 b8fc166d-592f-0410-95f2-cb63ce0dd405
Corrected comment.

git-svn-id: http://svn.boost.org/svn/boost/trunk@84117 b8fc166d-592f-0410-95f2-cb63ce0dd405
Fix #8066: Conflict with Boost.Log on GCC 4.4

git-svn-id: http://svn.boost.org/svn/boost/trunk@84118 b8fc166d-592f-0410-95f2-cb63ce0dd405