I've built pl/v8 for PostgreSQL 9.5 both 32-bit and 64-bit.
I built basically using these instructions on my gist gist page.
I've listed below PL/V8 binaries I built for PostgreSQL 9.5 for windows 64-bit and 32-bit. These I tested with EDB PostgreSQL 9.5 windows installs and seem to work fine and also passed all regression tests. These were built with PLV8 v1.4.4.
We hope windows users find these useful.