Switch from max_align_t to mjtNum until we sort out the git builds

PiperOrigin-RevId: 558982369
Change-Id: I24d9fd6400dae5e1bc1753ee74484da635ea8ecd

src/engine/engine_io.c

@@ -1213,8 +1213,9 @@ void* mj_stackAllocBytes(mjData* d, size_t size) {
   // start of the memory to be allocated to the buffer
   uintptr_t start_ptr = end_ptr - (size + mjREDZONE);
 
-  // move start_ptr back to align to max_align_t
-  start_ptr -= start_ptr % _Alignof(max_align_t);
+  // move start_ptr back to align to mjtNum
+  // TODO: switch to max_align_t
+  start_ptr -= start_ptr % _Alignof(mjtNum);
 
   // new top of the stack
   uintptr_t new_pstack_ptr = start_ptr - mjREDZONE;

test/engine/engine_util_container_test.cc

@@ -42,7 +42,7 @@ TEST(TestMjArrayList, TestMjArrayListSingleThreaded) {
 
   // Approximately (3 * sizeof(int) + 3 * sizeof(mjArrayList)) / sizeof(mjtNum)
   // However there is padding for alignment/etc.
-  EXPECT_EQ(d->maxuse_stack, 54);
+  EXPECT_EQ(d->maxuse_stack, 53);
 
   for (int i = 0; i < 35; ++i) {
     EXPECT_EQ(*(int*)mju_arrayListAt(array_list, i), i);