Fix array.sort in stdlib
For example:
```nickel
- sort (fun x y => if x < y then `Less else if (x == y) then `Equal else `Greater) [ 4, 5, 1, 2 ] =>
+ sort (fun x y => if x < y then `Lesser else if (x == y) then `Equal else `Greater) [ 4, 5, 1, 2 ] =>
[ 1, 2, 4, 5 ]
```
"%m
= fun cmp l =>
let first = %head% l in
- let parts = partition (fun x => (cmp x first == `Less)) (%tail% l) in
+ let parts = partition (fun x => (cmp x first == `Lesser)) (%tail% l) in
if %length% l <= 1 then
l
else
