libbb: add optionl support for SHA256/512 encrypted passwords

function                                             old     new   delta
sha_crypt                                              -    2423   +2423
cryptpw_main                                         128     183     +55
to64                                                   -      29     +29
pw_encrypt                                           974    1000     +26
str_rounds                                             -      11     +11
login_main                                          1532    1541      +9
packed_usage                                       25215   25200     -15
__md5_to64                                            29       -     -29
------------------------------------------------------------------------------
(add/remove: 3/1 grow/shrink: 3/1 up/down: 2553/-44)         Total: 2509 bytes

1 files changed, 2 insertions, 12 deletions

diff --git a/libbb/pw_encrypt_md5.c b/libbb/pw_encrypt_md5.c
index 8d0a516cf..b7478aa9d 100644
--- a/libbb/pw_encrypt_md5.c
+++ b/libbb/pw_encrypt_md5.c
@@ -494,16 +494,6 @@ static void __md5_Transform(uint32_t state[4], const unsigned char block[64])
 }
 
 
-static char*
-__md5_to64(char *s, unsigned v, int n)
-{
-        while (--n >= 0) {
-                *s++ = ascii64[v & 0x3f];
-                v >>= 6;
-        }
-        return s;
-}
-
 /*
  * UNIX password
  *
@@ -605,9 +595,9 @@ md5_crypt(char passwd[MD5_OUT_BUFSIZE], const unsigned char *pw, const unsigned
         final[16] = final[5];
         for (i = 0; i < 5; i++) {
                 unsigned l = (final[i] << 16) | (final[i+6] << 8) | final[i+12];
-                p = __md5_to64(p, l, 4);
+                p = to64(p, l, 4);
         }
-        p = __md5_to64(p, final[11], 2);
+        p = to64(p, final[11], 2);
         *p = '\0';
 
         /* Don't leave anything around in vm they could use. */