OSV-2024-859 Heap-double-free in libssh2_default_free

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=69726 Crash type: Heap-double-free Crash state: libssh2defaultfree diffiehellmanshaalgo kexmethoddiffiehellmangroup14keyexchange...