Mark up type_erasure failures.

git-svn-id: http://svn.boost.org/svn/boost/trunk@83614 b8fc166d-592f-0410-95f2-cb63ce0dd405
test_class& is not const.

git-svn-id: http://svn.boost.org/svn/boost/trunk@83615 b8fc166d-592f-0410-95f2-cb63ce0dd405
Prevent the move constructor from being elided.  This should fix the remaining clang failures in this test case.

git-svn-id: http://svn.boost.org/svn/boost/trunk@83616 b8fc166d-592f-0410-95f2-cb63ce0dd405