Please, support 64-bit seed. This is needed for compatibility with ffmpeg

I'm attempting to generate the same murmur3 hash values as ffmpeg generates. But it seems to use particular 64-bit seed ( https://git.ffmpeg.org/gitweb/ffmpeg.git/blob/1617d1a752d5e97d5e74f6c384609c027c884553:/libavutil/murmur3.c#l48 ). So, please, support 64-bit seeds