Boost.Python doesn't work on Sun-5.8. Mark it unusable.

[SVN r34854]

status/explicit-failures-markup.xml

@@ -3145,6 +3145,14 @@ for more information.
             the case. This is fixed in a later release.
             </note>
         </mark-unusable>
+        <mark-unusable>
+            <toolset name="sun-5.8*"/>
+            <note author="David Abrahams">
+            This compiler seems to be having trouble digesting
+            Boost.Tuple.  Until it can handle Boost.Tuple there's
+            little chance it will handle Boost.Python
+            </note>
+        </mark-unusable>
         <mark-expected-failures>
             <test name="args"/>
             <test name="auto_ptr"/>