testsuites/samples/fileio - Increase of stack size

When I use the 'shell' from the fileio sample with the command below:

   env QEMU_AUDIO_DRV="none" \
   qemu-system-arm -no-reboot -net none -nographic -M realview-pbx-a9 \
   -m 256M \
   -kernel build/arm/realview_pbx_a9_qemu/testsuites/samples/fileio.exe

The executable crashes with an "BLOWN STACK!!!" as soon as I try to login
as 'root' with password. (The logins without password work fine.)
Increasing the stack size of the affected thread a bit solves the issue.
Hence, I suggest this patch.

 My config.ini was

[arm/realview_pbx_a9_qemu]
RTEMS_DEBUG = True
RTEMS_NETWORKING = True
RTEMS_POSIX_API = True
RTEMS_SMP = True
BUILD_TESTS = True

RTEMS origin.master at a479686c11

Close #4143

testsuites/samples/fileio/init.c

@@ -630,7 +630,7 @@ static void fileio_start_shell(void)
   printf(" =========================\n");
   rtems_shell_init(
     "SHLL",                          /* task_name */
-    RTEMS_MINIMUM_STACK_SIZE * 4,    /* task_stacksize */
+    RTEMS_MINIMUM_STACK_SIZE * 5,    /* task_stacksize */
     100,                             /* task_priority */
     "/dev/foobar",                   /* devname */
     /* device is currently ignored by the shell if it is not a pty */