check if KDE is >= 4.2

Signed-off-by: David Tardon <dtardon@redhat.com>

configure.in

@@ -6992,6 +6992,21 @@ the root of your Qt installation by exporting QT4DIR before running "configure".
    KDE4_CFLAGS="`pkg-config --cflags QtCore` `pkg-config --cflags QtGui` -I$kde_incdir -DQT_CLEAN_NAMESPACE -DQT_THREAD_SUPPORT"
    KDE4_LIBS="-L$kde_libdir -L$qt_lib_dir -lkdeui -lkdecore -lQtCore -lQtGui"
 
+   AC_LANG_PUSH([C++])
+   save_CXXFLAGS=$CXXFLAGS
+   CXXFLAGS="$CXXFLAGS $KDE4_CFLAGS"
+   AC_MSG_CHECKING([whether KDE is >= 4.2])
+       AC_TRY_RUN([
+#include <kdeversion.h>
+
+int main(int argc, char **argv) {
+       if (KDE_VERSION_MAJOR == 4 && KDE_VERSION_MINOR >= 2) return 0;
+       else return 1;
+}
+       ], [AC_MSG_RESULT([yes])], [AC_MSG_ERROR([KDE version too old])])
+   CXXFLAGS=$save_CXXFLAGS
+   AC_LANG_POP([C++])
+
    # Glib is needed for properly handling Qt event loop with Qt's Glib integration enabled
    PKG_CHECK_MODULES(KDE_GLIB,[glib-2.0 >= 2.4],
     [KDE_HAVE_GLIB=1],