Building mkpasswd on Android makes no sense.

And won't work anyway because we don't have crypt(3).

toys/other/mkpasswd.c

diff --git a/toys/other/mkpasswd.c b/toys/other/mkpasswd.c
index 2e1c1a9..fe1bd26 100644
--- a/toys/other/mkpasswd.c
+++ b/toys/other/mkpasswd.c
@@ -10,6 +10,7 @@
 config MKPASSWD
   bool "mkpasswd"
   default y
+  depends on !TOYBOX_ON_ANDROID
   help
     usage: mkpasswd [-P FD] [-m TYPE] [-S SALT] [PASSWORD] [SALT]