Makefile $MACHDEPPATH uses $PLATDIR, but this variable was removed.
So remove also $MACHDEPPATH.
Remove also $EXTRAMACHDEPPATH.
# Standard path components for test modules
TESTPATH=
-# Path components for machine- or system-dependent modules and shared libraries
-MACHDEPPATH=:$(PLATDIR)
-EXTRAMACHDEPPATH=
-
-COREPYTHONPATH=$(DESTPATH)$(SITEPATH)$(TESTPATH)$(MACHDEPPATH)$(EXTRAMACHDEPPATH)
+COREPYTHONPATH=$(DESTPATH)$(SITEPATH)$(TESTPATH)
PYTHONPATH=$(COREPYTHONPATH)