devel/qt6-base: Enable building with non-base SSL
Fix detection of desired SSL provider. Previously, qt6-base was only
using OpenSSL from base, but this change allows users to build against
whichever SSL provider they have chosen via DEFAULT_VERSIONS.
LibreSSL support has also been added and is largely based on patches
obtained from the OpenBSD ports tree. Fixes [1].
Subsequently, refresh old patches.
PR: 269316 [1]
Reported by: <tjlegg@gmail.com> [1]
MFH: 2023Q4 (after 1 week)