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

diff --git a/coreutils/Kbuild b/coreutils/Kbuild
index a5a2d4c..67c5658 100644
--- a/coreutils/Kbuild
+++ b/coreutils/Kbuild
@@ -62,6 +62,8 @@
 lib-$(CONFIG_RMDIR)     += rmdir.o
 lib-$(CONFIG_SEQ)       += seq.o
 lib-$(CONFIG_SHA1SUM)   += md5_sha1_sum.o
+lib-$(CONFIG_SHA256SUM) += md5_sha1_sum.o
+lib-$(CONFIG_SHA512SUM) += md5_sha1_sum.o
 lib-$(CONFIG_SLEEP)     += sleep.o
 lib-$(CONFIG_SPLIT)     += split.o
 lib-$(CONFIG_SORT)      += sort.o