Mark known failure when do not support is_abstract

[SVN r37119]

status/explicit-failures-markup.xml

@@ -445,6 +445,16 @@
                 <note author="Douglas Gregor" refid="3"/>
             </mark-failure>
         </test>
+        <test name="lexical_cast_abstract_test">
+            <mark-failure>
+                <toolset name="borland-5.6*"/>
+                <toolset name="borland-5.8*"/>
+                <toolset name="borland-5.9*"/>
+                <note author="Alisdair Meredith">
+                    This compiler does not support the is_abstract type trait
+                </note>
+            </mark-failure>
+        </test>
     </library>
 
     <!-- crc -->