testjwt crashes during running tests when compiled with gnutls

[zdohnal]

Describe the bug
Test suite fails when cups built with gnutls - testjwt crashes due freeing already freed pointer:

To Reproduce
$ ./configure --with-tls=gnutls && make test

Running JSON API tests...
Running JWT API tests...
munmap_chunk(): invalid pointer

Expected behavior
Tests passed (or at least do not crash on the test)

System Information:

• tested on Fedora 41
• CUPS master branch

Additional context
Any additional information which are relevant to the issue.

[zdohnal]

PR #1287

[zdohnal]

The crash is fixed by the PR, but we have to investigate why GNUTLS returns error next.

[michaelrsweet]

I fixed this last week and forgot to close this issue. I was referencing the wrong algorithms for the Elliptical Curve functions.