p11-kit: do not use libiconv where not needed

Building libiconv even fails on Linux due to missing gets.
fontconfig: update 2.10.2 -> 2.11.1. Close #4410, #2050
fontconfig: add an upstream bugfix, remove other config inclusion
pango: big update; it was waiting on fontconfig-2.11
gst-1 video-related bumps (released yesterday)

pitivi looks fine, CC @iyzsong.
gtk3 stack libs: update all to gnome-3.14 branches

All NEWS look safe and relatively quiet.