Fixes this warning:
/builddir/build/BUILD/polymake-4.5/include/core/polymake/internal/AVL.h:52:6: warning: type ‘pm::AVL::Ptr_flags’ violates the C++ One Definition Rule [-Wodr]
52 | enum Ptr_flags : size_t {
| ^
/builddir/build/BUILD/polymake-4.5/include/core/polymake/internal/AVL.h:52:6: note: an enum with different value name is defined in another translation unit
52 | enum Ptr_flags : size_t {
| ^
/builddir/build/BUILD/polymake-4.5/include/core/polymake/internal/AVL.h:53:4: note: name ‘NONE’ differs from name ‘END_RING’ defined in another translation unit
53 | NONE=0,
| ^
/builddir/build/BUILD/polymake-4.5/include/core/polymake/internal/AVL.h:53:4: note: mismatching definition
53 | NONE=0,
| ^
--- lib/core/include/internal/AVL.h.orig 2021-09-29 06:13:35.000000000 -0600
+++ lib/core/include/internal/AVL.h 2021-10-04 06:41:35.414976853 -0600
@@ -33,6 +33,9 @@
#include <algorithm>
#include <cassert>
+// Avoid name clash with Singular
+#undef NONE
+
namespace pm {
/// special tags for find_nearest denoting the first and last occurrence of a given key in a multi-set