Add mjData.L, sparse Cholesky factor of Newton solver Hessian.

PiperOrigin-RevId: 683669555
Change-Id: I18d7530b5d68d1d48cb95d4faa0150c434109638

src/engine/engine_core_constraint.c

@@ -71,11 +71,10 @@ static int arenaAllocEfc(const mjModel* m, mjData* d) {
     return 0;                                                                 \
   }
 
-  MJDATA_ARENA_POINTERS_PRIMAL
+  MJDATA_ARENA_POINTERS_SOLVER
   if (mj_isDual(m)) {
     MJDATA_ARENA_POINTERS_DUAL
   }
-
 #undef X
 
 #undef MJ_M
@@ -1918,7 +1917,7 @@ static int mj_nc(const mjModel* m, mjData* d, int* nnz) {
 // driver: call all functions above
 void mj_makeConstraint(const mjModel* m, mjData* d) {
   // clear sizes
-  d->ne = d->nf = d->nl = d->nefc = d->nnzJ = 0;
+  d->ne = d->nf = d->nl = d->nefc = d->nnzJ = d->nnzL = 0;
 
   // disabled or Jacobian not allocated: return
   if (mjDISABLED(mjDSBL_CONSTRAINT)) {

src/engine/engine_io.c

@@ -1768,12 +1768,13 @@ static void _resetData(const mjModel* m, mjData* d, unsigned char debug_value) {
   mju_zero(d->solver_fwdinv, 2);
 
   // clear variable sizes
+  d->ncon = 0;
   d->ne = 0;
   d->nf = 0;
   d->nl = 0;
   d->nefc = 0;
   d->nnzJ = 0;
-  d->ncon = 0;
+  d->nnzL = 0;
   d->nisland = 0;
 
   // clear global properties