Give hint that openssl php extension is missing

[tag6]

Description

On Synology DSM I installed librespeed in 2023, it worked fine. Never cared about it until today. After I updated librespeed today via git, the download rate was very slow. Upload was fine. It took me quite some time to find out that the missing openssl extension is the cause (see https://github.com/librespeed/speedtest/issues/494) and how to enable it on Apache WebServer running on Synology DSM.

I'd like to have a warning if the preconditions to run librespeed are not fulfilled.

Why it should be implemented

Anyone who sees slow download rates that are caused by this issue should be informed that the network probably is not the problem, but the PHP installation misses the OpenSSL PHP-module.

Optional: implementation suggestions

I don't know what causes librespeed to be working but extremely slow in download without openssl. If the cause is not clear, it may be suitable to check if openssl module is active and output a warning if it isn't. Otherwise it would be even better not to rely on openssl.