minico fails to build with Clang 19

[jbeich]

From error log:

$ export CC=clang CXX=clang++
$ cmake -G Ninja -B _build
$ cmake --build _build
[...]
In file included from examples/minico/main.cpp:7:
In file included from como/base/wayland/platform.h:15:
como/render/wayland/platform.h:255:19: error: no member named 'addRepaintFull' in 'platform<Base>'; did you mean 'addRepaint'?
  255 |             this->addRepaintFull();
      |                   ^~~~~~~~~~~~~~
      |                   addRepaint
como/render/wayland/platform.h:220:10: note: 'addRepaint' declared here
  220 |     void addRepaint(QRegion const& region)
      |          ^

Also affects theseus-ship. Downstream simply removed unlock() methods. Only lock() method is actually used:

como/como/base/wayland/platform_helpers.h

Lines 51 to 53 in b5f18e9

	// Block compositor to prevent further compositing from crashing with a null workspace.
	// TODO(romangg): Instead we should kill the compositor before that or remove all outputs.
	platform.mod.render->lock();