Mark prg_exec_fail2 / darwin-4.0.1 failure as expected

[SVN r36797]

status/explicit-failures-markup.xml

@@ -3689,6 +3689,17 @@ for more information.
           <toolset name="cw-9.4"/>
           <note refid="29" author="Doug Gregor"/>
         </mark-expected-failures>
+
+        <mark-expected-failures>
+            <test name="prg_exec_fail2"/>
+            <toolset name="darwin-4.0.1"/>
+            <note author="Vladimir Prus">
+              The test appears to test that division by zero is
+              detected by Boost.Test. This is not happening on
+              Darwin, for unknown reasons.
+            </note>
+        </mark-expected-failures>
+
     </library>