readlink -f does not work on macos, let's use something portable.

Author: JulienPalard

Makefile

@@ -29,7 +29,7 @@ ifneq "$(shell cd $(CPYTHON_CLONE) 2>/dev/null && git describe --contains --all
 	$(warning "Your ../cpython checkout is on the wrong branch, got $(shell cd $(CPYTHON_CLONE) 2>/dev/null && git describe --contains --all HEAD) expected $(BRANCH)")
 endif
 	mkdir -p $(CPYTHON_CLONE)/locales/$(LANGUAGE)/
-	ln -nfs $(shell readlink -f .) $(CPYTHON_CLONE)/locales/$(LANGUAGE)/LC_MESSAGES
+	ln -nfs $(shell $(PYTHON) -c 'import os; print(os.path.realpath("."))') $(CPYTHON_CLONE)/locales/$(LANGUAGE)/LC_MESSAGES
 	$(MAKE) -C $(CPYTHON_CLONE)/Doc/ VENVDIR=$(VENV) PYTHON=$(PYTHON) SPHINXOPTS='-qaEW -j$(JOBS) -D locale_dirs=../locales -D language=$(LANGUAGE) -D gettext_compact=0 -D latex_engine=xelatex -D latex_elements.inputenc= -D latex_elements.fontenc=' $(MODE)