Only try to run krandrstartup if it exists wrt bug #524266.

After f7f5d84c85b6c7f946b94808849648b4cb6ea667, krandrstartup is no longer
available if kde-base/systemsettings is built with USE="kscreen". Otherwise,
KDE will fail to start

Source: http://pkgs.fedoraproject.org/cgit/kde-workspace.git/tree/startkde.cmake
diff --git a/startkde.cmake b/startkde.cmake
index afc2cfb..4220e64 100644
--- a/startkde.cmake
+++ b/startkde.cmake
@@ -105,7 +105,7 @@ if test -n "$kcminputrc_mouse_cursortheme" -o -n "$kcminputrc_mouse_cursorsize"
     fi
 fi
 
-. krandrstartup
+KRANDRSTARTUP=`which krandrstartup 2>/dev/null` && . $KRANDRSTARTUP
 
 if test "$kcmfonts_general_forcefontdpi" -ne 0; then
     xrdb -quiet -merge -nocpp <<EOF