[geometry] update buffer unit tests for gcc

git-svn-id: http://svn.boost.org/svn/boost/trunk@83997 b8fc166d-592f-0410-95f2-cb63ce0dd405
[geometry] fix for clang

git-svn-id: http://svn.boost.org/svn/boost/trunk@83998 b8fc166d-592f-0410-95f2-cb63ce0dd405