plasma-desktop: disable the tablet KCM pending a libwacom port

plasma-workspace now builds and installs, so plasma-desktop configured for the
first time and stopped at:
  The following required packages were not found: - libwacom

kcms/tablet requires libwacom (CMakeLists.txt:175), which is not ported -- it
needs libgudev plus upstream's tablet-definition database. Disabled via
upstream's own option (CMakeLists.txt:44, default ON), not an invented switch;
it gates exactly three sources (tabletsmodel.cpp, kcmtablet.cpp,
tabletmoduledata.cpp) and nothing else in plasma-desktop is affected.

THIS REMOVES THE DRAWING-TABLET SETTINGS MODULE. Tracked as a real port; the
option goes back ON in the same change that lands libwacom.

local/recipes/kde/plasma-desktop/recipe.toml

@@ -82,7 +82,22 @@ done
 # yields invalid C++. Idempotent.
 python3 "${COOKBOOK_ROOT}/local/scripts/gate-kx11extras.py" "${COOKBOOK_SOURCE}"
 
+# BUILD_KCM_TABLET=OFF -- THIS REMOVES THE DRAWING-TABLET SETTINGS MODULE.
+#
+# kcms/tablet requires libwacom (CMakeLists.txt:175,
+# pkg_check_modules(LIBWACOM libwacom REQUIRED)), which is not ported: it needs
+# libgudev plus upstream's tablet-definition database. Without it configure
+# aborts outright:
+#   The following required packages were not found: - libwacom
+#
+# This is upstream's own option (CMakeLists.txt:44, default ON), not an
+# invented switch, and it gates exactly three sources -- tabletsmodel.cpp,
+# kcmtablet.cpp, tabletmoduledata.cpp. Everything else in plasma-desktop is
+# unaffected.
+#
+# Tracked for a real port; turn back ON in the same change that lands libwacom.
 cmake "${COOKBOOK_SOURCE}" \
+    -DBUILD_KCM_TABLET=OFF \
     -DKF_SKIP_PO_PROCESSING=ON \
     -DCMAKE_TOOLCHAIN_FILE="${COOKBOOK_ROOT}/local/recipes/qt/redox-toolchain.cmake" \
     -DQT_HOST_PATH="${HOST_BUILD}" \