Fix incompatible pointer type using explicit noop functions

[MatthiasKunnen]

On master, building results in the following errors.

../src/outputs.c:529:15: error: initialization of ‘void (*)(void *, struct zwlr_output_manager_v1 *)’ from incompatible pointer type ‘void (*)(void)’ [-Wincompatible-pointer-types]
  529 |   .finished = noop,
      |               ^~~~
../src/outputs.c:529:15: note: (near initialization for ‘output_manager_listener.finished’)
../src/outputs.c:31:13: note: ‘noop’ declared here
   31 | static void noop() {
      |             ^~~~
../src/outputs.c:556:20: error: initialization of ‘void (*)(void *, struct wl_registry *, uint32_t)’ {aka ‘void (*)(void *, struct wl_registry *, unsigned int)’} from incompatible pointer type ‘void (*)(void)’ [-Wincompatible-pointer-types]
  556 |   .global_remove = noop,
      |                    ^~~~
../src/outputs.c:556:20: note: (near initialization for ‘registry_listener.global_remove’)
../src/outputs.c:31:13: note: ‘noop’ declared here
   31 | static void noop() {
      |             ^~~~
../src/outputs.c:606:19: error: initialization of ‘void (*)(void *, struct zxdg_output_v1 *, int32_t,  int32_t)’ {aka ‘void (*)(void *, struct zxdg_output_v1 *, int,  int)’} from incompatible pointer type ‘void (*)(void)’ [-Wincompatible-pointer-types]
  606 |   .logical_size = noop,
      |                   ^~~~
../src/outputs.c:606:19: note: (near initialization for ‘output_listener.logical_size’)
../src/outputs.c:31:13: note: ‘noop’ declared here
   31 | static void noop() {
      |             ^~~~
../src/outputs.c:607:11: error: initialization of ‘void (*)(void *, struct zxdg_output_v1 *)’ from incompatible pointer type ‘void (*)(void)’ [-Wincompatible-pointer-types]
  607 |   .done = noop,
      |           ^~~~
../src/outputs.c:607:11: note: (near initialization for ‘output_listener.done’)
../src/outputs.c:31:13: note: ‘noop’ declared here
   31 | static void noop() {
      |             ^~~~
../src/outputs.c:609:18: error: initialization of ‘void (*)(void *, struct zxdg_output_v1 *, const char *)’ from incompatible pointer type ‘void (*)(void)’ [-Wincompatible-pointer-types]
  609 |   .description = noop
      |                  ^~~~

This PR replaces the generic noop function with explicit ones. Argument names are taking from the respective wayland protocols.

Closes #25.
Closes #27.