Make libcef_dll_wrapper.libs build with VS2013

This should be the first and last time we need this fix because it's
fixed upstream in CEF see
https://code.google.com/p/chromiumembedded/issues/detail?id=1094 - but
that is unfortunately after the official pristine binary release at
r1562

Former-commit-id: 646e40bf6b4682c2ac75100282bf3ff89dccb8c3

Author: jornh