Remove solver_nisland field from mjData.

PiperOrigin-RevId: 750527660
Change-Id: I6b34944c92483ea2abc774df75efd868255a2bac

simulate/simulate.cc

@@ -298,7 +298,7 @@ void UpdateProfiler(mj::Simulate* sim, const mjModel* m, const mjData* d) {
   memset(sim->figcost.linepnt, 0, mjMAXLINE*sizeof(int));
 
   // number of islands that have diagnostics
-  int nisland = mjMIN(d->solver_nisland, mjNISLAND);
+  int nisland = mjMAX(1, mjMIN(d->nisland, mjNISLAND));
 
   // iterate over islands
   for (int k=0; k < nisland; k++) {
@@ -413,7 +413,7 @@ void UpdateProfiler(mj::Simulate* sim, const mjModel* m, const mjData* d) {
     static_cast<float>(d->nefc),
     static_cast<float>(sqrt_nnz),
     static_cast<float>(d->ncon),
-    static_cast<float>(solver_niter)
+    static_cast<float>(solver_niter) / nisland
   };
 
   // update figsize
@@ -582,7 +582,7 @@ void UpdateInfoText(mj::Simulate* sim, const mjModel* m, const mjData* d,
   char tmp[20];
 
   // number of islands with statistics
-  int nisland = mjMIN(d->solver_nisland, mjNISLAND);
+  int nisland = mjMAX(1, mjMIN(d->nisland, mjNISLAND));
 
   // compute solver error (maximum over islands)
   mjtNum solerr = 0;