v8: Fix mac build: snapshot filename
v8: Fix mac build: snapshot filename

https://github.com/nwjs/v8/commit/3068a7f75a393661e34ed3cf36ddec78ae79dacd

nwjs/nw.js,nwjs/nw.js,nwjs/nw.js,nwjs/nw.js,nwjs/nw.js,nwjs/nw.js