Kernel: Assert if rounding-up-to-page-size would wrap around to 0

If we try to align a number above 0xfffff000 to the next multiple of
the page size (4 KiB), it would wrap around to 0. This is most likely
never what we want, so let's assert if that happens.

Kernel/Heap/kmalloc.cpp

@@ -108,7 +108,7 @@ struct KmallocGlobalHeap {
             // was big enough to likely satisfy the request
             if (subheap.free_bytes() < allocation_request) {
                 // Looks like we probably need more
-                size_t memory_size = PAGE_ROUND_UP(decltype(m_global_heap.m_heap)::calculate_memory_for_bytes(allocation_request));
+                size_t memory_size = page_round_up(decltype(m_global_heap.m_heap)::calculate_memory_for_bytes(allocation_request));
                 // Add some more to the new heap. We're already using it for other
                 // allocations not including the original allocation_request
                 // that triggered heap expansion. If we don't allocate