samples: shell_module: fix missing qsort reference

PR #39980 added qsort to minimal libc but caused
shell_modules sample to fail building.

Signed-off-by: Sylvio Alves <[email protected]>

Author: sylvioalves

samples/subsys/shell/shell_module/src/dynamic_cmd.c

@@ -7,6 +7,7 @@
 #include <shell/shell.h>
 #include <ctype.h>
 #include <stdio.h>
+#include <stdlib.h>
 
 #define MAX_CMD_CNT (20u)
 #define MAX_CMD_LEN (33u)