Big-endian architecture support in nginx-rtmp-module

In branch big-endian of nginx-rtmp-module there's experimental support for big-endian architectures like MIPS and big-endian ARM. If you have such devices (eg. routers) please try installing nginx-rtmp on them and report the result. I've tested live streaming which is OK. In theory everything should work fine, but I still need more responses before merging the branch