removed vc8 markup in conversion

[SVN r32309]

status/explicit-failures-markup.xml

@@ -357,10 +357,6 @@
     <!-- conversion -->
     <library name="conversion">
         <test name="lexical_cast_test">
-            <mark-failure>
-                <toolset name="vc-8_0"/>
-                <note author="Aleksey Gurtovoy" refid="4"/>
-            </mark-failure>
             <mark-failure>
                 <toolset name="sunpro-5_3-sunos"/>
                 <note author="Douglas Gregor" refid="3"/>