add missing .c_str() (closes #10337)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@58115 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/urlmsw.cpp

@@ -173,7 +173,7 @@ size_t wxWinINetInputStream::OnSysRead(void *buffer, size_t bufsize)
             );
 
             wxLogError(wxT("Read failed with error %d: %s"),
-                       iError, errorString);
+                       iError, errorString.c_str());
         }
     }