deps: v8 build on FreeBSD 10.2
Building v3.2.0 with clang 3.4.1 get error: reinterpret_cast from 'nullptr_t' to 'v8::internal::Smi *' is not allowed
. Fix proposed matches approach by @indutny to fix issue #324 (closed) in commit https://github.com/indutny/io.js/commit/d9977e8f1ff6ac64bfc7e0c0907f27ec020eff80