[boost] [assign] list_inserter regression test failure on VC10 / release branch

Another minor regression test fix: The list_inserter regression test (libs\assign\test\list_inserter.cpp) was fixed for VC10 on the Trunk in revision 62737, but hasn't yet been merged to the release branch. (the change also fixes one of the errors from GCC/C++0x, but the test still fails for other reasons).