markup accumulators library test that may take too long to compile with aC++

[SVN r49938]

status/explicit-failures-markup.xml

@@ -68,6 +68,7 @@
       <mark-expected-failures>
         <test name="covariance"/>
         <test name="pot_quantile"/>
+        <test name="tail_variate_means"/>
         <test name="weighted_covariance"/>
         <test name="weighted_pot_quantile"/>
         <test name="weighted_tail_variate_means"/>