Check TLS 64bytes support by environment variable

[horstle]

As discussed in #450

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[dtechsrv]

I pushed the patches and the necessary post-fixes to the LE and CE team.

I received a feedback from CoreELEC (by @Portisch) that my pull request would be merged after the next ISH release, that handles the LIBC_WIDEVINE_PATCHLEVEL environment variable.
I haven't received any feedback from LibreELEC yet, but I hope they do the same.
I also got a feedback from LibreELEC (by @CvH), they will do the same.

So everyone is really looking forward to ISH version 0.5.7.
Thank you all for your efforts. ;-)

[dtechsrv]

Can we somehow speed up the merging of this PR and the preparation for the release of v0.5.7?

[horstle]

I'd have preferred to test it a little, but since it's not a big change, I'll merge it now.