Revert "nettle 2.7.1"

The library version has changed in this version, breaking reverse
dependencies (e.g. gnutls). It needs to wait for revisions.

This reverts commit 3c39f2e43121d695e0ad53d6a21927f43cb9b667.
vcodex: update urls

Fixes #25443.
Closes #25474.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
doxygen 1.8.6

Closes #25473.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
libmicrohttpd 0.9.33

Closes #25472.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>