Merge #834: qt, build: remove unneeded Q_IMPORT_PLUGIN macro calls

7346b01 qt, build: remove unneeded `Q_IMPORT_PLUGIN` macro calls (Sebastian Falbesoner)

Pull request description:

  After the recent full removal of Autotools (PR [#30664](bitcoin/bitcoin#30664)), these macros are not needed anymore in the .cpp files according to the TODO in qt's CMakeLists.txt. Tested building on OpenBSD 7.5, where the XCB plugin was still imported according to the debug log:
  ```
  2024-09-02T21:13:27Z Bitcoin Core version v28.99.0-7346b0109208 (release build)
  2024-09-02T21:13:27Z Qt 5.15.12 (dynamic), plugin=xcb
  2024-09-02T21:13:27Z No static plugins.
  2024-09-02T21:13:27Z Style: fusion / QFusionStyle
  2024-09-02T21:13:27Z System: OpenBSD 7.5, x86_64-little_endian-lp64
  ```

ACKs for top commit:
  hebasto:
    ACK 7346b01.

Tree-SHA512: ffa033fc6e0412a99d2c167044cc7af89512a731172d6911db71434f5353e811802c268d853a76d3732e9da954444cf6c39a852aeb25938c435826e117a16fca

src/qt/CMakeLists.txt

@@ -13,9 +13,6 @@ endif()
 
 get_target_property(qt_lib_type Qt5::Core TYPE)
 
-# TODO: After the transition from Autotools to CMake,
-#       all `Q_IMPORT_PLUGIN` macros can be deleted from the
-#       qt/bitcoin.cpp and qt/test/test_main.cpp source files.
 function(import_plugins target)
   if(qt_lib_type STREQUAL "STATIC_LIBRARY")
     set(plugins Qt5::QMinimalIntegrationPlugin)

src/qt/bitcoin.cpp

@@ -60,21 +60,6 @@
 #include <QTranslator>
 #include <QWindow>
 
-#if defined(QT_STATIC)
-#include <QtPlugin>
-#if defined(QT_QPA_PLATFORM_XCB)
-Q_IMPORT_PLUGIN(QXcbIntegrationPlugin);
-#elif defined(QT_QPA_PLATFORM_WINDOWS)
-Q_IMPORT_PLUGIN(QWindowsIntegrationPlugin);
-Q_IMPORT_PLUGIN(QWindowsVistaStylePlugin);
-#elif defined(QT_QPA_PLATFORM_COCOA)
-Q_IMPORT_PLUGIN(QCocoaIntegrationPlugin);
-Q_IMPORT_PLUGIN(QMacStylePlugin);
-#elif defined(QT_QPA_PLATFORM_ANDROID)
-Q_IMPORT_PLUGIN(QAndroidPlatformIntegrationPlugin)
-#endif
-#endif
-
 // Declare meta types used for QMetaObject::invokeMethod
 Q_DECLARE_METATYPE(bool*)
 Q_DECLARE_METATYPE(CAmount)

src/qt/test/test_main.cpp

@@ -28,22 +28,6 @@
 
 #include <functional>
 
-#if defined(QT_STATIC)
-#include <QtPlugin>
-#if defined(QT_QPA_PLATFORM_MINIMAL)
-Q_IMPORT_PLUGIN(QMinimalIntegrationPlugin);
-#endif
-#if defined(QT_QPA_PLATFORM_XCB)
-Q_IMPORT_PLUGIN(QXcbIntegrationPlugin);
-#elif defined(QT_QPA_PLATFORM_WINDOWS)
-Q_IMPORT_PLUGIN(QWindowsIntegrationPlugin);
-#elif defined(QT_QPA_PLATFORM_COCOA)
-Q_IMPORT_PLUGIN(QCocoaIntegrationPlugin);
-#elif defined(QT_QPA_PLATFORM_ANDROID)
-Q_IMPORT_PLUGIN(QAndroidPlatformIntegrationPlugin)
-#endif
-#endif
-
 const std::function<void(const std::string&)> G_TEST_LOG_FUN{};
 
 const std::function<std::vector<const char*>()> G_TEST_COMMAND_LINE_ARGUMENTS{};