Mark program_options unusable on VC 7.0

[SVN r29941]

status/explicit-failures-markup.xml

@@ -1910,6 +1910,10 @@ for more information.
             <note refid="17"/>
         </mark-unusable>
 
+        <mark-unusable>
+            <toolset name="vc-7_0"/>
+            <note refid="29"/>
+        </mark-unusable>
 
         <!-- Mark expected failures -->