Unix sys/resource.h types and bindings (getrlimit, setrlimit, and friends)

unix-sys-resource provides access to the features exposed in sys/resource.h in a way that is not tied to the implementation on the host system.

The Sys_resource module provides types and functions for describing and working with rlimit resources and limits.

The Sys_resource_unix module provides bindings to functions that use the types in Sys_resource.

Currently, getrlimit and setrlimit and their corresponding flags are bound.