cmake: Add WITH_DBUS option

CMakeLists.txt

@@ -151,11 +151,16 @@ if(WITH_QRENCODE)
   set(USE_QRCODE TRUE)
 endif()
 
+cmake_dependent_option(WITH_DBUS "Enable DBus support." ON "CMAKE_SYSTEM_NAME STREQUAL \"Linux\" AND BUILD_GUI" OFF)
 if(BUILD_GUI)
   set(qt_components Core Gui Widgets LinguistTools)
   if(ENABLE_WALLET)
     list(APPEND qt_components Network)
   endif()
+  if(WITH_DBUS)
+    list(APPEND qt_components DBus)
+    set(USE_DBUS TRUE)
+  endif()
   find_package(Qt5 5.11.3 MODULE REQUIRED
     COMPONENTS ${qt_components}
   )
@@ -498,6 +503,7 @@ message("   - using UPnP ....................... ${WITH_MINIUPNPC}")
 message("  ZeroMQ .............................. ${WITH_ZMQ}")
 message("  USDT tracing ........................ ${WITH_USDT}")
 message("  QR code (GUI) ....................... ${WITH_QRENCODE}")
+message("  DBus (GUI, Linux only) .............. ${WITH_DBUS}")
 message("Tests:")
 message("  test_bitcoin ........................ ${BUILD_TESTS}")
 message("  bench_bitcoin ....................... ${BUILD_BENCH}")