rmmod: fix bad error message

    Before:

    ># busybox_old rmmod gtrhfhdfghdf
    rmmod: can't unload 'gtrhfhdfghdf': unknown symbol in module, or unknown parameter

    After:

    ># busybox rmmod gtrhfhdfghdf
    rmmod: can't unload module 'gtrhfhdfghdf': No such file or directory

function                                             old     new   delta
modprobe_main                                        726     721      -5
do_modprobe                                          599     590      -9
rmmod_main                                           187     169     -18
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-32)             Total: -32 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/modutils/modutils.c b/modutils/modutils.c
index 84300d9..ef4134a 100644
--- a/modutils/modutils.c
+++ b/modutils/modutils.c
@@ -190,6 +190,11 @@
 	return errno;
 }
 
+/* Note: not suitable for delete_module() errnos.
+ * For them, probably only EWOULDBLOCK needs explaining:
+ * "Other modules depend on us". So far we don't do such
+ * translation and don't use moderror() for removal errors.
+ */
 const char* FAST_FUNC moderror(int err)
 {
 	switch (err) {