Avoid 0-length memmove from buffer end to keep static analyzers happier

This avoid incorrect errors from some static analyzers that do not like
memmove with pointers just after the end of a buffer even if the number
of bytes to move is zero.

Signed-hostap: Jouni Malinen <j@w1.fi>

src/eap_server/eap_server.c

@@ -1028,9 +1028,12 @@ void eap_sm_process_nak(struct eap_sm *sm, const u8 *nak_list, size_t len)
 
 	not_found:
 		/* not found - remove from the list */
-		os_memmove(&sm->user->methods[i], &sm->user->methods[i + 1],
-			   (EAP_MAX_METHODS - i - 1) *
-			   sizeof(sm->user->methods[0]));
+		if (i + 1 < EAP_MAX_METHODS) {
+			os_memmove(&sm->user->methods[i],
+				   &sm->user->methods[i + 1],
+				   (EAP_MAX_METHODS - i - 1) *
+				   sizeof(sm->user->methods[0]));
+		}
 		sm->user->methods[EAP_MAX_METHODS - 1].vendor =
 			EAP_VENDOR_IETF;
 		sm->user->methods[EAP_MAX_METHODS - 1].method = EAP_TYPE_NONE;