Boost.Log merged to trunk.

git-svn-id: http://svn.boost.org/svn/boost/trunk@83860 b8fc166d-592f-0410-95f2-cb63ce0dd405
Corrected exception type when an unsupported placeholder is found in the file name pattern when scanning the filesystem.

git-svn-id: http://svn.boost.org/svn/boost/trunk@83862 b8fc166d-592f-0410-95f2-cb63ce0dd405