[openssl/openssl] 3c0e8b: fix for sslecho in demos echoing garbage #18165

[pauli]

  Branch: refs/heads/master
  Home:   https://github.openssl.org/openssl/openssl
  Commit: 3c0e8bc4a797d29b2152aebc6e687ddfa941160b
      https://github.openssl.org/openssl/openssl/commit/3c0e8bc4a797d29b2152aebc6e687ddfa941160b
  Author: philippe lhardy <pl at artisanlogiciel.net>
  Date:   2022-05-06 (Fri, 06 May 2022)

  Changed paths:
    M demos/sslecho/main.c

  Log Message:
  -----------
  fix for sslecho in demos echoing garbage #18165

- getline does set &txbufp content at return, make sure it can be done.
  - fixes warning 'passing argument 1 of ‘getline’ from incompatible pointer type'
- remove OPENSSL_free on non allocated fixed size array
  - fixes 'free(): invalid pointer'

Reviewed-by: Tomas Mraz <tomas at openssl.org>
Reviewed-by: Paul Dale <pauli at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18177)