sha: reduce sha256/512 context size. Make sha1/sha256 code more similar

function                                             old     new   delta
sha512_end                                           182     204     +22
sha256_end                                           137     147     +10
sha1_hash                                            113     108      -5
sha1_end                                             143     129     -14
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(add/remove: 0/0 grow/shrink: 2/2 up/down: 32/-19)             Total: 13 bytes

2 files changed