Add maxuse_threadstack to mjData

PiperOrigin-RevId: 567334177
Change-Id: Ifd772350042e548a63ab269fd68fb5e5fef55831

src/engine/engine_util_misc.h

@@ -122,6 +122,9 @@ MJAPI int mju_isZero(mjtNum* vec, int n);
 // set integer vector to 0
 MJAPI void mju_zeroInt(int* res, int n);
 
+// set size_t vector to 0
+MJAPI void mju_zeroSizeT(size_t* res, size_t n);
+
 // copy int vector vec into res
 MJAPI void mju_copyInt(int* res, const int* vec, int n);