libbb: move crypt_make_salt() to pw_encrypt.c, reuse
bin-to-ascii64 conversion which does not require an array.

function                                             old     new   delta
to64                                                  29      33      +4
to64_msb_first                                        63      62      -1
ascii64                                               65       -     -65

diff --git a/libbb/Kbuild b/libbb/Kbuild
index b82f03c..2c8830f 100644
--- a/libbb/Kbuild
+++ b/libbb/Kbuild
@@ -120,9 +120,9 @@
 lib-$(CONFIG_FEATURE_MOUNT_LOOP) += loop.o
 lib-$(CONFIG_LOSETUP) += loop.o
 lib-$(CONFIG_FEATURE_MTAB_SUPPORT) += mtab.o
-lib-$(CONFIG_PASSWD) += pw_encrypt.o crypt_make_salt.o update_passwd.o
-lib-$(CONFIG_CHPASSWD) += pw_encrypt.o crypt_make_salt.o update_passwd.o
-lib-$(CONFIG_CRYPTPW) += pw_encrypt.o crypt_make_salt.o
+lib-$(CONFIG_PASSWD) += pw_encrypt.o update_passwd.o
+lib-$(CONFIG_CHPASSWD) += pw_encrypt.o update_passwd.o
+lib-$(CONFIG_CRYPTPW) += pw_encrypt.o
 lib-$(CONFIG_SULOGIN) += pw_encrypt.o
 lib-$(CONFIG_FEATURE_HTTPD_AUTH_MD5) += pw_encrypt.o
 lib-$(CONFIG_VLOCK) += pw_encrypt.o correct_password.o