On Linux we use `sysinfo(2)` to look up the load average.
Factor out a dedicated source file to make this implementation
available for use on other platforms that support it.
PR-URL: https://github.com/libuv/libuv/pull/1312
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
