Rename mj_stackAllocByte to mj_stackAlloc and make it public.

PiperOrigin-RevId: 561133040
Change-Id: I4f5ffe51c1287aa0c82af68bfe17ed6dd2ad09da

src/engine/engine_io.h

@@ -20,7 +20,10 @@
 #include <mujoco/mjmodel.h>
 
 #ifdef __cplusplus
+#include <cstddef>
 extern "C" {
+#else
+#include <stddef.h>
 #endif
 
 // internal hash map size factor (2 corresponds to a load factor of 0.5)
@@ -100,7 +103,10 @@ MJAPI void mj_resetDataDebug(const mjModel* m, mjData* d, unsigned char debug_va
 MJAPI void mj_resetDataKeyframe(const mjModel* m, mjData* d, int key);
 
 // mjData arena allocate
-MJAPI void* mj_arenaAlloc(mjData* d, int bytes, int alignment);
+MJAPI void* mj_arenaAlloc(mjData* d, size_t bytes, size_t alignment);
+
+// mjData stack allocate
+MJAPI void* mj_stackAlloc(mjData* d, size_t bytes, size_t alignment);
 
 // mjData stack allocate for array of mjtNums
 MJAPI mjtNum* mj_stackAllocNum(mjData* d, int size);
@@ -108,9 +114,6 @@ MJAPI mjtNum* mj_stackAllocNum(mjData* d, int size);
 // mjData stack allocate for array of ints
 MJAPI int* mj_stackAllocInt(mjData* d, int size);
 
-// mjData stack allocate for a specific size of bytes
-MJAPI void* mj_stackAllocByte(mjData* d, size_t size);
-
 // de-allocate data
 MJAPI void mj_deleteData(mjData* d);