Resolve a build failure on ILP32.

References: https://gist.github.com/benlorenz/76b0cc37e332943e0129e1e922a1b577

Index: polymake-4.7/apps/topaz/include/grass_plucker.h
===================================================================
--- polymake-4.7.orig/apps/topaz/include/grass_plucker.h
+++ polymake-4.7/apps/topaz/include/grass_plucker.h
@@ -122,7 +122,7 @@ using CubeIndex = NamedType<Int, CubeInd
   inline constexpr Int max_n_vertices(31); 
   inline constexpr Int first_cube_index(Int(1) << max_n_vertices);
 */
-#define max_n_vertices 31
+#define max_n_vertices ((Int) sizeof(Int)*4-1)
 #define first_cube_index (CubeIndex(Int(1) << (2*max_n_vertices)))
 #define MAGIC_VERTEX_MULTIPLE 256