Use cudaMallocManaged by default

We should use system malloc by default for large allocations so that we
can get the CUDA memory management. The removes the VALGRIND flag.
mymalloc calls now use the cuda allocation, but tamalloc continue to use
a private cpu heap.

libgadget/utils/mymalloc.c

@@ -21,10 +21,6 @@ Allocator A_MAIN[1];
  * */
 Allocator A_TEMP[1];
 
-#ifdef VALGRIND
-#define allocator_init allocator_malloc_init
-#endif
-
 void
 tamalloc_init(void)
 {
@@ -64,7 +60,7 @@ mymalloc_init(double MaxMemSizePerNode)
         endrun(2, "Mem too small! MB/node=%g, nodespercpu = %g NTask = %d\n", MaxMemSizePerNode, nodespercpu, NTask);
 
 
-    if (MPIU_Any(ALLOC_ENOMEMORY == allocator_init(A_MAIN, "MAIN", n, 1, NULL), MPI_COMM_WORLD)) {
+    if (MPIU_Any(ALLOC_ENOMEMORY == allocator_malloc_init(A_MAIN, "MAIN", n, 1, NULL), MPI_COMM_WORLD)) {
         endrun(0, "Insufficient memory for the MAIN allocator on at least one nodes."
                   "Requestion %td bytes. Try reducing MaxMemSizePerNode. Also check the node health status.\n", n);
     }