In an editable install of sagelib (#31377), the tdlib subdirectory is considered as a namespace package directory, shadowing the sage.graphs.graph_decompositions.tdlib module, causing the failures reported on that ticket.

We fix this by moving the file tdlib/sage_tdlib.cpp (the only file in that subdirectory) one level higher.

CC: @dcoudert @dimpase @tobiasdiez

Component: graph theory

Author: Matthias Koeppe

Branch/Commit: 19ca17a

Reviewer: David Coudert

Issue created by migration from https://trac.sagemath.org/ticket/31389