removed unusability mark for multi_index on sun-5.8 to see if things have improved

[SVN r35628]

status/explicit-failures-markup.xml

@@ -2005,7 +2005,6 @@ for more information.
         <mark-unusable>
             <toolset name="sunpro-5_3-sunos"/>
             <toolset name="sunpro-5_8u1-sunos"/>
-            <toolset name="sun-5.8"/>
             <note author="J. L&#243;pez" date="22 Apr 2005" refid="17"/>
         </mark-unusable>
         <mark-unusable>