Fix small bug in computation of dx for swallowed angular momentum of black holes.

This merge request fixes a (very) small bug in the computation of dx between a black hole and its to-be-swallowed gas particle neighbour. This only affected the swallowed angular momentum output variable.

src/black_holes/EAGLE/black_holes.h

@@ -268,8 +268,8 @@ __attribute__((always_inline)) INLINE static void black_holes_swallow_part(
 
   /* Physical distance between the particles */
   const float dx[3] = {(bp->x[0] - p->x[0]) * cosmo->a,
-                       (bp->x[0] - p->x[0]) * cosmo->a,
-                       (bp->x[0] - p->x[0]) * cosmo->a};
+                       (bp->x[1] - p->x[1]) * cosmo->a,
+                       (bp->x[2] - p->x[2]) * cosmo->a};
 
   /* Collect the swallowed angular momentum */
   bp->swallowed_angular_momentum[0] +=