This patch contains more safe checking in syscall rlimit and unit tests

The soft limit is the value that the kernel enforces for the corresponding resource
The hard limit acts as a ceiling for the soft limit
an unprivileged process may only set its soft limit to a value
in the range from 0 up to the hard limit.
So in order to make the change in fds count without any error we should
inform the user to make the process have CAP_SYS_RESOURCE capability
in order to set the hard limit.

License: MIT
Signed-off-by: hoenirvili <hoenirvili@gmail.com>