Free the offsets array at the end of the particle sorting routines.

Unless I am mistaken about the logic here. we should free the offset array at the end of the function.

Also, should we use an aligned allocation here? The memswap function documentation begs the user to use aligned addresses but that may not apply to things smaller than an AVX vector.

src/space.c

@@ -1420,7 +1420,9 @@ void space_parts_sort(struct part *parts, struct xpart *xparts, int *ind,
   for (int k = 0; k < num_bins; k++)
     if (offsets[k + 1] != offsets[k] + counts[k])
       error("Bad offsets after shuffle.");
-#endif  // SWIFT_DEBUG_CHECKS
+#endif /* SWIFT_DEBUG_CHECKS */
+
+  free(offsets);
 }
 
 /**
@@ -1475,7 +1477,9 @@ void space_sparts_sort(struct spart *sparts, int *ind, int *counts,
   for (int k = 0; k < num_bins; k++)
     if (offsets[k + 1] != offsets[k] + counts[k])
       error("Bad offsets after shuffle.");
-#endif  // SWIFT_DEBUG_CHECKS
+#endif /* SWIFT_DEBUG_CHECKS */
+
+  free(offsets);
 }
 
 /**
@@ -1537,7 +1541,9 @@ void space_gparts_sort(struct gpart *gparts, struct part *parts,
   for (int k = 0; k < num_bins; k++)
     if (offsets[k + 1] != offsets[k] + counts[k])
       error("Bad offsets after shuffle.");
-#endif  // SWIFT_DEBUG_CHECKS
+#endif /* SWIFT_DEBUG_CHECKS */
+
+  free(offsets);
 }
 
 /**