Add cmake stub for qt_internal_add_shaders in qtdeclarative

Qt6ShaderTools cmake function is not available in our cross-compilation
setup. Added -C preload with no-op stub function to allow cmake
configuration to proceed past shader compilation calls.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

recipes/wip/qt/qtdeclarative/recipe.toml

@@ -129,7 +129,15 @@ text = text.replace('if(TARGET Qt::Gui AND TARGET Qt::qsb AND QT_FEATURE_qml_ani
 path.write_text(text)
 PY
 
+cat > "${COOKBOOK_BUILD}/shader_stub.cmake" << 'EOFCMAKE'
+function(qt_internal_add_shaders target name)
+endfunction()
+function(qt_internal_add_shader_helpers target name)
+endfunction()
+EOFCMAKE
+
 cmake "${COOKBOOK_SOURCE}" \
+    -C "${COOKBOOK_BUILD}/shader_stub.cmake" \
     -DCMAKE_TOOLCHAIN_FILE="${COOKBOOK_ROOT}/local/recipes/qt/redox-toolchain.cmake" \
     -DQT_HOST_PATH="${HOST_BUILD}" \
     -DCMAKE_INSTALL_PREFIX=/usr \