BUILD: debug: fix build issue on 32-bit platforms in "debug dev task"

Commit 986798718 ("DEBUG: cli: add "debug dev task" to show/wake/expire/kill
tasks and tasklets") caused a build failure on 32-bit platforms when parsing
the task's pointer. Let's use strtoul() and not strtoll(). No backport is
needed, unless the commit above gets backported.
diff --git a/src/debug.c b/src/debug.c
index 8d87530..67711e1 100644
--- a/src/debug.c
+++ b/src/debug.c
@@ -982,7 +982,7 @@
 		return 1;
 
 	/* parse the pointer value */
-	ptr = (void *)strtoll(args[3], &endarg, 0);
+	ptr = (void *)strtoul(args[3], &endarg, 0);
 	if (!*args[3] || *endarg)
 		goto usage;