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: https://github.com/winft/como/blob/b5f18e92c2ce76d8640ada51a47638b3a003cee8/como/base/wayland/platform_helpers.h#L51-L53