commands/memtools: Add memtool module with memory allocation stress-test

When working on memory, it's nice to be able to test your work.

Add a memtest module. When compiled with --enable-mm-debug, it exposes
3 commands:

 * lsmem - print all allocations and free space in all regions
 * lsfreemem - print free space in all regions

 * stress_big_allocs - stress test large allocations:
  - how much memory can we allocate in one chunk?
  - how many 1MB chunks can we allocate?
  - check that gap-filling works with a 1MB aligned 900kB alloc + a
     100kB alloc.

Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Tested-by: Nageswara R Sastry <rnsastry@linux.ibm.com>
Reviewed-by: Robbie Harwood <rharwood@redhat.com>

grub-core/kern/mm.c

@@ -734,6 +734,8 @@ grub_mm_dump_free (void)
     {
       grub_mm_header_t p;
 
+      grub_printf ("Region %p (size %" PRIuGRUB_SIZE ")\n\n", r, r->size);
+
       /* Follow the free list.  */
       p = r->first;
       do
@@ -761,6 +763,8 @@ grub_mm_dump (unsigned lineno)
     {
       grub_mm_header_t p;
 
+      grub_printf ("Region %p (size %" PRIuGRUB_SIZE ")\n\n", r, r->size);
+
       for (p = (grub_mm_header_t) ALIGN_UP ((grub_addr_t) (r + 1),
 					    GRUB_MM_ALIGN);
 	   (grub_addr_t) p < (grub_addr_t) (r+1) + r->size;