gdk-pixbuf: bump to version 2.36.5

gdk-pixbuf: bump to version 2.36.5

This release needs a new tweak regarding loaders.cache - it's now used
to build the thumbnailer.
Since we already generate it using the host variant for the target we
can re-use this for the build step.
It's not necessary to used the tweaked version since the build one is
only used to account for mime types, not the plugins/loaders themselves.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>