Avoid using X11 if qmmp is built without X but qtbase has xcb feature.
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -99,8 +99,9 @@ set(USE_SKINNED TRUE CACHE BOOL "enable/disable standard skinned user interface"
 set(USE_DIR_ASSOC TRUE CACHE BOOL "enable/disable inode/directory mime type association")
 #set(APP_NAME_SUFFIX "-1")
 
+option(USE_XCB "Use xcb if available in QtGui" ON)
 get_target_property(QtGui_enabled_features Qt6::Gui QT_ENABLED_PUBLIC_FEATURES)
-if("xcb" IN_LIST QtGui_enabled_features)
+if(USE_XCB AND "xcb" IN_LIST QtGui_enabled_features)
     pkg_search_module(X11 x11 IMPORTED_TARGET)
     set(XCB_ENABLED YES)
     add_definitions(-DQMMP_WS_X11)