[openssl/openssl] 4343b2: unbuffer stdin before get passwd from stdin

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  Branch: refs/heads/openssl-3.0
  Home:   https://github.com/openssl/openssl
  Commit: 4343b2923ac2f50c78bb7438374d5dc47958ad8b
      https://github.com/openssl/openssl/commit/4343b2923ac2f50c78bb7438374d5dc47958ad8b
  Author: wangyuhang <524413304 at qq.com>
  Date:   2022-12-12 (Mon, 12 Dec 2022)

  Changed paths:
    M apps/lib/apps.c

  Log Message:
  -----------
  unbuffer stdin before get passwd from stdin

commond LD_LIBRARY_PATH= openssl rsa -aes256 -passout stdin <<< "xxxxxx” will get pass(fun app_get_pass()) from stdin first, and then load key(fun load_key()). but it unbuffer stdin before load key, this will cause the load key to fail.

now unbuffer stdin before get pass, this will solve https://github.com/openssl/openssl/issues/19835

CLA: trivial

Reviewed-by: Tomas Mraz <tomas at openssl.org>
Reviewed-by: Paul Dale <pauli at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19851)

(cherry picked from commit efec0f4611ee854f2b0b3da0c135e839bf8e7d04)