Split phony targets

Makefile

@@ -1,7 +1,6 @@
-# https://www.gnu.org/software/make/manual/html_node/Phony-Targets.html
-.PHONY: clean co coverage doc doccheck docserve help inplace install install-coverage debug install-req install-venv release-test sdist test readme
 .DEFAULT_GOAL := release-test
 
+.PHONY: clean
 clean:
 	python3 setup.py clean
 	rm src/PIL/*.so || true
@@ -9,28 +8,34 @@ clean:
 	find . -name __pycache__ | xargs rm -r || true
 
 BRANCHES=`git branch -a | grep -v HEAD | grep -v master | grep remote`
+.PHONY: co
 co:
 	-for i in $(BRANCHES) ; do \
         git checkout -t $$i ; \
     done
 
+.PHONY: coverage
 coverage:
 	pytest -qq
 	rm -r htmlcov || true
 	coverage report
 
+.PHONY: doc
 doc:
 	$(MAKE) -C docs html
 
+.PHONY: doccheck
 doccheck:
 	$(MAKE) -C docs html
 # Don't make our tests rely on the links in the docs being up every single build.
 # We don't control them.  But do check, and update them to the target of their redirects.
 	$(MAKE) -C docs linkcheck || true
 
+.PHONY: docserve
 docserve:
 	cd docs/_build/html && python3 -mSimpleHTTPServer 2> /dev/null&
 
+.PHONY: help
 help:
 	@echo "Welcome to Pillow development. Please use \`make <target>\` where <target> is one of"
 	@echo "  clean              remove build products"
@@ -48,17 +53,21 @@ help:
 	@echo "  upload             build and upload sdists to PyPI"
 	@echo "  upload-test        build and upload sdists to test.pythonpackages.com"
 
+.PHONY: inplace
 inplace: clean
 	python3 setup.py develop build_ext --inplace
 
+.PHONY: install
 install:
 	python3 setup.py install
 	python3 selftest.py
 
+.PHONY: install-coverage
 install-coverage:
 	CFLAGS="-coverage" python3 setup.py build_ext install
 	python3 selftest.py
 
+.PHONY: debug
 debug:
 # make a debug version if we don't have a -dbg python. Leaves in symbols
 # for our stuff, kills optimization, and redirects to dev null so we
@@ -66,13 +75,16 @@ debug:
 	make clean > /dev/null
 	CFLAGS='-g -O0' python3 setup.py build_ext install > /dev/null
 
+.PHONY: install-req
 install-req:
 	python3 -m pip install -r requirements.txt
 
+.PHONY: install-venv
 install-venv:
 	virtualenv .
 	bin/pip install -r requirements.txt
 
+.PHONY: release-test
 release-test:
 	$(MAKE) install-req
 	python3 setup.py develop
@@ -84,11 +96,14 @@ release-test:
 	pyroma .
 	viewdoc
 
+.PHONY: sdist
 sdist:
 	python3 setup.py sdist --format=gztar
 
+.PHONY: test
 test:
 	pytest -qq
 
+.PHONY: readme
 readme:
 	viewdoc