fix typo in vc-7_1-stlport toolset name

[SVN r30782]

status/explicit-failures-markup.xml

@@ -873,7 +873,7 @@
             <toolset name="vc-6_5*"/>
             <toolset name="vc-7_0"/>
             <toolset name="vc-7_1"/>
-            <toolset name="vc- 7_1-stlport"/>
+            <toolset name="vc-7_1-stlport"/>
             <toolset name="vc-8_0"/>
             <toolset name="borland-5_6_4"/>
             <toolset name="gcc-2*"/>