GUI: Qt6: actively check if QMediaPlayer is available instead of version check

ac/qt5.m4

@@ -229,6 +229,7 @@ EOF
   AC_MSG_CHECKING(for Qt 5)
 
   if test x"$problem" = x; then
+    AC_DEFINE(HAVE_QMEDIAPLAYER, 1, [Define to 1 if you have the QMediaPlayer header file.])
     AC_DEFINE(HAVE_QT, 1, [Define if Qt is present])
     AC_MSG_RESULT(yes)
     have_qt5=yes

ac/qt6.m4

@@ -202,6 +202,13 @@ return 0;
     return
   fi
 
+  AC_LANG_PUSH(C++)
+  ac_save_CXXFLAGS="$CXXFLAGS"
+  CXXFLAGS="$STD_CXX $CXXFLAGS $QT_CFLAGS -fPIC"
+  AC_CHECK_HEADERS([QMediaPlayer])
+  CXXFLAGS="$ac_save_CXXFLAGS"
+  AC_LANG_POP()
+
   AC_DEFINE(HAVE_QT, 1, [Define if Qt is present])
   AC_MSG_CHECKING(for Qt 6)
   AC_MSG_RESULT(yes)

src/mkvtoolnix-gui/util/media_player.cpp

@@ -2,10 +2,10 @@
 
 #include <Qt>
 
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
+#if HAVE_QMEDIAPLYER
 # include <QMediaPlayer>
 
-#else  // Qt < 6
+#else  // HAVE_QMEDIAPLAYER
 # include <QUrl>
 
 // Fake Media Player class as Qt 6.1 hasn't re-added the media framework yet.
@@ -22,7 +22,7 @@ public:
   void stop() {}
 };
 
-#endif  // Qt < 6
+#endif  // HAVE_QMEDIAPLAYER
 
 #include "mkvtoolnix-gui/util/media_player.h"