Stop mapping Meta to Super

A lot of X11 keyboard layouts send Meta for Shift-Alt so it's not
really a good idea to assume this is the Windows key.
diff --git a/vncviewer/Viewport.cxx b/vncviewer/Viewport.cxx
index 4daff16..b319a81 100644
--- a/vncviewer/Viewport.cxx
+++ b/vncviewer/Viewport.cxx
@@ -782,11 +782,9 @@
     // For the first few years, there wasn't a good consensus on what the
     // Windows keys should be mapped to for X11. So we need to help out a
     // bit and map all variants to the same key...
-    case XK_Meta_L:
     case XK_Hyper_L:
       keysym = XK_Super_L;
       break;
-    case XK_Meta_R:
     case XK_Hyper_R:
       keysym = XK_Super_R;
       break;