Clang 3.5 reports error: memset overwrites vtable pointer in s2

src/third_party/s2/s2regioncoverer.cc:116:10: error: destination for this 'memset' call is a pointer to class containing a dynamic class

      'S2Cell'; vtable pointer will be overwritten [-Werror,-Wdynamic-class-memaccess]

  memset(candidate, 0, size);

  ~~~~~~ ^

src/third_party/s2/s2regioncoverer.cc:116:10: note: explicitly cast the pointer to silence this warning

  memset(candidate, 0, size);

         ^

         (void*)

1 error generated.