Use backslashes in VS 10 library dependencies

The list of libraries to be linked into the current target must be
specified using windows slashes to that UNC paths such as

  \\server\share\somelibrary.lib

work correctly.  See issue #9917.

Source/cmVisualStudio10TargetGenerator.cxx

@@ -1222,6 +1222,7 @@ void cmVisualStudio10TargetGenerator::AddLibraries(
         Convert(l->Value.c_str(),
                 cmLocalGenerator::START_OUTPUT,
                 cmLocalGenerator::UNCHANGED);
+      this->ConvertToWindowsSlash(path);
       libstring += sep;
       libstring += path;
       }