some more scons cleanup

git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@1414 8ced0084-cf51-0410-be5f-012b33b47a6e

Source/Plugins/Plugin_PadSimple/Src/SConscript

@@ -5,6 +5,10 @@ import sys
 
 name = "Plugin_PadSimple"
 
+if not env['HAVE_X11']:
+    print name + " must have X11 to be build"
+    Return()
+
 files = [
 	"PadSimple.cpp",
 	]