fix --enable-redis-igbinary

--enable-redis-igbinary was broken, because the igbinary_serializer and igbinary_unserializer functions could not be found. This commit fixes it by compiling the igbinary sources into php-redis.dll, just like it did before https://github.com/vostok4/phpredis/commit/b7e8b3b64edbfc6583f551a22c9d2186625e19c9

Compiled binaries are at http://www.apachelounge.com/viewtopic.php?t=5900