Issue #20306: Android is the only system that returns NULL for the pw_passwd

field.  Rather than cluttering the tests, translate the arguably more correct
"None" to an empty string.

Modules/pwdmodule.c

@@ -75,7 +75,7 @@ mkpwent(struct passwd *p)
 #define SETS(i,val) sets(v, i, val)
 
     SETS(setIndex++, p->pw_name);
-#if defined(HAVE_STRUCT_PASSWD_PW_PASSWD)
+#if defined(HAVE_STRUCT_PASSWD_PW_PASSWD) && !defined(__ANDROID__)
     SETS(setIndex++, p->pw_passwd);
 #else
     SETS(setIndex++, "");