Return list of 1 minute, 5 minute and 15 minute load averages.
Each of the three load averages is multiplied by 100, then converted
to integer.
When USE-FLOATS is non-nil, floats will be used instead of integers.
These floats are not multiplied by 100.
If the 5-minute or 15-minute load averages are not available, return a
shortened list, containing only those averages which are available.
An error is thrown if the load average can't be obtained. In some
cases making it work would require Emacs being installed setuid or
setgid so that it can read kernel information, and that usually isn't
advisable.
(fn &optional USE-FLOATS)