p11-kit: bump to version 0.23.1

It's required for the new gnutls version, fixes:
http://autobuild.buildroot.net/results/3ec/3ecac965455dc169162cbdb50f8ff07e2880e504/

Patch status: reported upstream:
https://bugs.freedesktop.org/show_bug.cgi?id=93211



Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>