silence warning in exec.c

Index: qemu/exec.c
===================================================================
@@ -2142,8 +2142,8 @@ ram_addr_t qemu_ram_alloc(ram_addr_t siz
 {
     ram_addr_t addr;
     if ((phys_ram_alloc_offset + size) > phys_ram_size) {
-        fprintf(stderr, "Not enough memory (requested_size = %lu, max memory = %ld)\n",
-                size, phys_ram_size);
+        fprintf(stderr, "Not enough memory (requested_size = %llu, max memory = %llu)\n",
+                (unsigned long long) size, (unsigned long long) phys_ram_size);
         abort();
     }
     addr = phys_ram_alloc_offset;