added pgi to toolsets expected to fail seekawble_file_test (iostreams)

[SVN r42827]

status/explicit-failures-markup.xml

@@ -2038,6 +2038,7 @@
             <toolset name="*como-4_3_3*"/>
             <toolset name="sun-5.*"/>
             <toolset name="*stlport"/>
+            <toolset name="pgi-7.0"/>
             <note author="Jonathan Turkanis" refid="4"/>
         </mark-expected-failures>
         <mark-expected-failures>