Avoid a FPE arising from compiler optimisation of the h < h_min branch of the ghost.

src/runner.c

@@ -1462,12 +1462,6 @@ void runner_do_ghost(struct runner *r, struct cell *c, int timer) {
             /* Ok, this particle is a lost cause... */
             p->h = hydro_h_min;
 
-            /* Do some damage control if no neighbours at all were found */
-            if (has_no_neighbours) {
-              hydro_part_has_no_neighbours(p, xp, cosmo);
-              chemistry_part_has_no_neighbours(p, xp, chemistry, cosmo);
-            }
-
           } else if (p->h >= hydro_h_max) {
 
             /* Ok, this particle is a lost cause... */

tests/test125cells.c

@@ -601,7 +601,7 @@ int main(int argc, char *argv[]) {
   hp.eta_neighbours = h;
   hp.h_tolerance = 1e0;
   hp.h_max = FLT_MAX;
-  hp.h_min = h / 1e6;
+  hp.h_min = 0.f;
   hp.h_min_ratio = 0.f;
   hp.max_smoothing_iterations = 10;
   hp.CFL_condition = 0.1;