bug#40829: [core-updates] pdfpc-4.3.4 fails to build

[Jack Hill]

Hi Guix,

Currently, pdfpc on core-updates fails to build with:

/tmp/guix-build-pdfpc-4.3.4.drv-0/source/src/classes/action/action_mapping.vala:51.9-51.28:
 error: Creation method of abstract class cannot be public.
        public ActionMapping() {
        ^^^^^^^^^^^^^^^^^^^^
/tmp/guix-build-pdfpc-4.3.4.drv-0/source/src/classes/drawings/storage.vala:38.9-38.19:
 error: Creation method of abstract class cannot be public.
        public Base(Metadata.Pdf metadata) {
        ^^^^^^^^^^^
/tmp/guix-build-pdfpc-4.3.4.drv-0/source/src/classes/renderer/cache/base.vala:40.9-40.19:
 error: Creation method of abstract class cannot be public.
        public Base(Metadata.Pdf metadata) {
        ^^^^^^^^^^^
/tmp/guix-build-pdfpc-4.3.4.drv-0/source/src/classes/timer_label.vala:98.9-98.25:
 error: Creation method of abstract class cannot be public.
        public TimerLabel(PresentationController controller, time_t start_time 
= 0) {
        ^^^^^^^^^^^^^^^^^
/tmp/guix-build-pdfpc-4.3.4.drv-0/source/src/classes/view/behaviour/base.vala:44.9-44.19:
 error: Creation method of abstract class cannot be public.
        public Base() {
        ^^^^^^^^^^^

Upgrading to the latest release, 4.4.0, solves the problem. I have 
prepared the following patch against core-updates that does that.

Best,
Jack