fix usage with setuptools

Current versions of setuptools overwrite distutils.
Therefore we have a new unwanted dependency.
This patch addresses this in the unit tests and fixes a bug caused by
calling uname during the bootstrapping of setuptools distutils package.

.github/workflows/unit_tests.yml

@@ -35,6 +35,7 @@ jobs:
     - name: Install Python packages
       run: |
         pip install --upgrade pip
+        pip install --upgrade setuptools
         pip install numpy mpi4py pytest
 
     - name: Build python bindings

scorep/subsystem.py

@@ -1,5 +1,4 @@
 import os
-import distutils.ccompiler
 import tempfile
 import shutil
 
@@ -86,7 +85,12 @@ def generate(scorep_config, keep_files=False):
 
     subsystem_lib_name = generate_subsystem_lib_name()
 
+    # setuptools, which replaces distutils, calls uname in python < 3.9 during distutils bootstraping.
+    # When LD_PRELOAD is set, this leads to preloading Score-P to uname, and crashes the later tracing.
+    # To avoid this, we need to do the distutils bootstrap as late as possible.
+    import distutils.ccompiler
     cc = distutils.ccompiler.new_compiler()
+
     compiled_subsystem = cc.compile(
         [temp_dir + "/scorep_init.c"], output_dir=temp_dir)
     cc.link(