nx-X11/config/cf: Clean-up left-overs from having our own libNX_Xext shared library.

nx-X11/config/cf/README

@@ -283,8 +283,6 @@ An <os>Lib.tmpl file provides defaults for the following variables:
 
 	SharedX11Reqs		required libs for libX11.so
 	SharedX11Rev		version number for libX11.so
-	SharedXextReqs		required libs for libXext.so
-	SharedXextRev		version number for libXext.so
 
 Vendor.cf files and/or site/host specific .def files may define the
 following variables:

nx-X11/config/cf/lnxLib.tmpl

@@ -3,6 +3,5 @@
  */
 
 #define SharedX11Reqs     $(LDPRELIB) -ldl -lXdmcp
-#define SharedXextReqs	  $(LDPRELIB) $(XONLYLIB)
 
 #define NoMessageCatalog