Fix build with Qt6 (probonopd#613)

find_package(QT ...) only finds out if Qt5 or Qt6 is available.
One needs to then to find_package(Qt5...) or find_package(Qt6...) as in
the Qt documentation:
https://doc.qt.io/qt-6/cmake-qt5-and-qt6-compatibility.html

Otherwise, one gets this error:
CMake Error: AUTOMOC for target linuxdeployqt: Could not find moc
executable target Qt6::moc
CMake Generate step failed.  Build files cannot be regenerated
correctly.

Co-authored-by: David Faure <faure@kde.org>

tools/linuxdeployqt/CMakeLists.txt

@@ -0,0 +1,31 @@
+set(CMAKE_AUTOMOC ON)
+
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+# expose version data as compiler definition
+add_definitions("-DLINUXDEPLOYQT_VERSION=\"${GIT_TAG_NAME}\"")
+add_definitions("-DLINUXDEPLOYQT_GIT_COMMIT=\"${GIT_COMMIT}\"")
+add_definitions("-DBUILD_DATE=\"${DATE}\"")
+add_definitions("-DBUILD_NUMBER=\"${BUILD_NUMBER}\"")
+
+find_package(QT NAMES Qt6 Qt5 REQUIRED COMPONENTS Core)
+find_package(Qt${QT_VERSION_MAJOR} REQUIRED COMPONENTS Core)
+
+# update excludelist
+message(STATUS "Updating excludelist...")
+execute_process(
+    COMMAND bash ${CMAKE_CURRENT_SOURCE_DIR}/../generate-excludelist.sh
+    OUTPUT_VARIABLE EXCLUDELIST
+    TIMEOUT 10
+    RESULT_VARIABLE EXCLUDELIST_RESULT
+)
+if(NOT EXCLUDELIST_RESULT EQUAL 0)
+    message(WARNING "Updating excludelist failed, using outdated copy")
+endif()
+mark_as_advanced(EXCLUDELIST EXCLUDELIST_RESULT)
+
+add_executable(linuxdeployqt main.cpp shared.cpp)
+target_include_directories(linuxdeployqt PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
+target_link_libraries(linuxdeployqt Qt${QT_VERSION_MAJOR}::Core)
+target_compile_definitions(linuxdeployqt PRIVATE -DEXCLUDELIST="${EXCLUDELIST}")