Merge topic branch t/openssl-3 into master

Two patches. The first suppresses warnings when compiling against
openssl-3, the second switches the two hash functions over to the
EVP API. More work is needed but it does not hurt to merge this first
step now.

* refs/heads/t/openssl-3:
  openssl: Switch to evp API for sha1 and sha256.
  openssl: Deactivate openssl-3 warnings for now.

diff --cc NEWS.md
index 009982a3b85a3ad2421aab8ef4684b3dc30a8587,5a00175c3255702b03ec86e0af1938863f53ba4d..fff7a242bba99d3a322b47c0d101d36b93e8d8d5
--- 1/NEWS.md
--- 2/NEWS.md
+++ b/NEWS.md
@@@ -1,21 -1,6 +1,23 @@@
  NEWS
  ====
  
 +------------------------------------------
 +0.7.2 (to be announced) "optical friction"
 +------------------------------------------
 +
 +- A major cleanup of the audio file selector.
 +- The client no longer prints error messages from afs commands to
 +  stdout but to stderr.
 +- The sleep subcommand of para_mixer gained two options to control
 +  the startup mood and the time period before fade-out starts. A bunch
 +  of further improvements for this subcommand went in as well.
 +- Minor cleanup of the net subsystem.
++- The openssl specific code now employs the EVP API to compute hashes.
++  It should compile without warnings against openssl-3.
 +
 +Downloads:
 +[tarball](./releases/paraslash-git.tar.xz)
 +
  --------------------------------------
  0.7.1 (2022-10-03) "digital spindrift"
  --------------------------------------