Remove duplicate definition of USE_GENERIC_DXERR_LIBRARY in ppremake

dtool/LocalSetup.pp

@@ -376,9 +376,6 @@ $[cdefine HAVE_CGDX9]
 /* Define if we have CGDX10 installed.  */
 $[cdefine HAVE_CGDX10]
 
-/* Define for dxerr.h instead of dxerr9.h. */
-$[cdefine USE_GENERIC_DXERR_LIBRARY]
-
 /* Define if we have zlib installed.  */
 $[cdefine HAVE_ZLIB]