CN: Fix source location in `resourceInference.ml`

[dc-mak]

This line

cerberus/backend/cn/lib/resourceInference.ml

Line 220 in d87e0f1

let here = Locations.other __LOC__ in

Gets into an error message here:

14:56 ➜  cerberus git:(cn-html-escape-ampersand) cn verify other_loc.c
[1/2]: single -- fail
[2/2]: tester -- fail
other_loc.c:20:1: error: Missing resource for returning
void single(cluster_t* cluster)
~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
Resource needed: Cluster(cluster)
      other_loc.c:25:10: (arg C2)
  which requires: RW<struct cluster_t>(cluster)
      other_loc.c:9:8: (arg Cluster)
  which requires: RW<signed int>(&cluster->size)
      other location (File "backend/cn/lib/resourceInference.ml", line 220, characters 31-38)  (arg size)  # <--- HERE!
State file: file:///tmp/state__other_loc.c__single.html
other_loc.c:56:9: error: Left-over unused resource 'Alloc(unpack_Cluster7.Cluster.chars)(unpack_Cluster7.A)'
        for (int i=0; i<cluster.size; i++)

Though I'm not exactly sure how, and how to fix it.

[dc-mak]

Here's the repo test case:

typedef struct cluster_t {
    int size; // Number in cluster
    char* chars; // Array in cluster
} cluster_t;

/*@
predicate { i32 size } Cluster(pointer p) {
  take Cluster = RW<cluster_t>(p);
  assert (Cluster.size >= 0i32);
  let A = allocs[(alloc_id)Cluster.chars];
  assert (A.size == (u64) Cluster.size);
  assert (A.base == (u64) Cluster.chars);
  assert (A.base <= A.base + A.size);
  take Chars = each (u64 j; 0u64 <= j && j < (u64) Cluster.size) { RW<char>(array_shift<char>(Cluster.chars, j)) };
  return { size: Cluster.size };
}
@*/

void single(cluster_t* cluster)
/*@
ensures
    take C2 = Cluster(cluster);
@*/
{
    for (int i = 0; i < cluster->size; i++)
    /*@ inv take C3 = Cluster(cluster);
            0i32 <= i; i <= C3.size;
            {cluster} unchanged;
    @*/
    {
        /*@ focus RW<char>, (u64) i; @*/
        cluster->chars[i];
    }
}