cmake: Allow WITH_DBUS on all Unix-like systems

This change makes the `WITH_DBUS` option available on all Unix-like
systems, not just Linux, thereby fixing a regression that was
overlooked during the migration from Autotools.

Note: Enabling D-Bus support on macOS still makes no sense, since the
`Notificator` class uses the User Notification Center regardless.

Author: hebasto

CMakeLists.txt

@@ -138,7 +138,7 @@ 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)
+cmake_dependent_option(WITH_DBUS "Enable DBus support." ON "NOT CMAKE_SYSTEM_NAME MATCHES \"(Windows|Darwin)\" AND BUILD_GUI" OFF)
 
 option(ENABLE_IPC "Build multiprocess bitcoin-node and bitcoin-gui executables in addition to monolithic bitcoind and bitcoin-qt executables. Requires libmultiprocess library. Experimental." OFF)
 cmake_dependent_option(WITH_EXTERNAL_LIBMULTIPROCESS "Build with external libmultiprocess library instead of with local git subtree when ENABLE_IPC is enabled. This is not normally recommended, but can be useful for developing libmultiprocess itself." OFF "ENABLE_IPC" OFF)
@@ -679,7 +679,7 @@ endif()
 message("  IPC ................................. ${ipc_status}")
 message("  USDT tracing ........................ ${WITH_USDT}")
 message("  QR code (GUI) ....................... ${WITH_QRENCODE}")
-message("  DBus (GUI, Linux only) .............. ${WITH_DBUS}")
+message("  DBus (GUI) .......................... ${WITH_DBUS}")
 message("Tests:")
 message("  test_bitcoin ........................ ${BUILD_TESTS}")
 message("  test_bitcoin-qt ..................... ${BUILD_GUI_TESTS}")