feat: use xcb private headers in qt-base-private dev

Link: deepin-community/qt6-base#26

Log:

Author: Cryolitia

xcb/linux.cmake

@@ -85,7 +85,11 @@ else()
             message(FATAL_ERROR "Not support Qt Version: ${Qt5_VERSION}")
         endif()
     elseif(${QT_VERSION_MAJOR} STREQUAL "6")
-        if(EXISTS ${CMAKE_CURRENT_LIST_DIR}/libqt6xcbqpa-dev/${Qt6_VERSION})
+        list(GET Qt6Core_INCLUDE_DIRS 0 dir)
+        string(REPLACE "QtCore" "QtXcb" Qt6Xcb_INCLUDE_DIR ${dir})
+        if(EXISTS ${Qt6Xcb_INCLUDE_DIR}/${Qt6_VERSION}/QtXcb/private)
+            include_directories(${Qt6Xcb_INCLUDE_DIR}/${Qt6_VERSION}/QtXcb/private)
+        elseif(EXISTS ${CMAKE_CURRENT_LIST_DIR}/libqt6xcbqpa-dev/${Qt6_VERSION})
             include_directories(${CMAKE_CURRENT_LIST_DIR}/libqt6xcbqpa-dev/${Qt6_VERSION})
         else()
             message(FATAL_ERROR "Not support Qt Version: ${Qt6_VERSION}")