Add constraint island discovery

PiperOrigin-RevId: 557067599
Change-Id: Ic41e1d0efef02b7a79142518afe49cf9d4e74725

src/engine/engine_core_constraint.h

@@ -18,6 +18,7 @@
 #include <mujoco/mjdata.h>
 #include <mujoco/mjexport.h>
 #include <mujoco/mjmodel.h>
+#include <mujoco/mjxmacro.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -115,12 +116,6 @@ MJAPI void mj_referenceConstraint(const mjModel* m, mjData* d);
 MJAPI void mj_constraintUpdate(const mjModel* m, mjData* d, const mjtNum* jar,
                                mjtNum cost[1], int flg_coneHessian);
 
-// construct sparse matrix from unsorted edge array, return number of nonzeros
-MJAPI int mj_edge2Sparse(int* rownnz, int* rowadr, int* colind, int* edge, int ne, int nr);
-
-MJAPI int mj_floodFill(int* island, int nr, const int* rownnz, const int* rowadr, const int* colind,
-                       int* scratch);
-
 #ifdef __cplusplus
 }
 #endif