Respect the DESTDIR variable during 'make install'

The DESTDIR variable used to tell 'make install' an alternate system root
to install the software to. Since setup.py supports the same via its --root
parameter, it's easy to make life easier for many packagers.

Makefile

@@ -1,109 +1,109 b''
 # If you want to change PREFIX, do not just edit it below. The changed
 # value wont get passed on to recursive make calls. You should instead
 # override the variable on the command like:
 #
 # % make PREFIX=/opt/ install
 
 PREFIX=/usr/local
 export PREFIX
 PYTHON=python
 PURE=
 PYTHON_FILES:=$(shell find mercurial hgext doc -name '*.py')
 
 help:
 	@echo 'Commonly used make targets:'
 	@echo '  all          - build program and documentation'
 	@echo '  install      - install program and man pages to PREFIX ($(PREFIX))'
 	@echo '  install-home - install with setup.py install --home=HOME ($(HOME))'
 	@echo '  local        - build for inplace usage'
 	@echo '  tests        - run all tests in the automatic test suite'
 	@echo '  test-foo     - run only specified tests (e.g. test-merge1)'
 	@echo '  dist         - run all tests and create a source tarball in dist/'
 	@echo '  clean        - remove files created by other targets'
 	@echo '                 (except installed files or dist source tarball)'
 	@echo '  update-pot   - update i18n/hg.pot'
 	@echo
 	@echo 'Example for a system-wide installation under /usr/local:'
 	@echo '  make all && su -c "make install" && hg version'
 	@echo
 	@echo 'Example for a local installation (usable in this directory):'
 	@echo '  make local && ./hg version'
 
 all: build doc
 
 local:
 	$(PYTHON) setup.py $(PURE) build_py -c -d . build_ext -i build_mo
 	$(PYTHON) hg version
 
 build:
 	$(PYTHON) setup.py $(PURE) build
 
 doc:
 	$(MAKE) -C doc
 
 clean:
 	-$(PYTHON) setup.py clean --all # ignore errors from this command
 	find . -name '*.py[cdo]' -exec rm -f '{}' ';'
 	rm -f MANIFEST mercurial/__version__.py mercurial/*.so tests/*.err
 	rm -rf mercurial/locale
 	$(MAKE) -C doc clean
 
 install: install-bin install-doc
 
 install-bin: build
-	$(PYTHON) setup.py $(PURE) install --prefix="$(PREFIX)" --force
+	$(PYTHON) setup.py $(PURE) install --root="$(DESTDIR)/" --prefix="$(PREFIX)" --force
 
 install-doc: doc
 	cd doc && $(MAKE) $(MFLAGS) install
 
 install-home: install-home-bin install-home-doc
 
 install-home-bin: build
 	$(PYTHON) setup.py $(PURE) install --home="$(HOME)" --force
 
 install-home-doc: doc
 	cd doc && $(MAKE) $(MFLAGS) PREFIX="$(HOME)" install
 
 MANIFEST-doc:
 	$(MAKE) -C doc MANIFEST
 
 MANIFEST: MANIFEST-doc
 	hg manifest > MANIFEST
 	echo mercurial/__version__.py >> MANIFEST
 	cat doc/MANIFEST >> MANIFEST
 
 dist:	tests dist-notests
 
 dist-notests:	doc MANIFEST
 	TAR_OPTIONS="--owner=root --group=root --mode=u+w,go-w,a+rX-s" $(PYTHON) setup.py -q sdist
 
 tests:
 	cd tests && $(PYTHON) run-tests.py $(TESTFLAGS)
 
 test-%:
 	cd tests && $(PYTHON) run-tests.py $(TESTFLAGS) $@
 
 update-pot: i18n/hg.pot
 
 i18n/hg.pot: $(PYTHON_FILES) mercurial/help/*.txt
 	$(PYTHON) i18n/hggettext mercurial/commands.py \
 	  hgext/*.py hgext/*/__init__.py mercurial/help/*.txt > i18n/hg.pot
         # All strings marked for translation in Mercurial contain
         # ASCII characters only. But some files contain string
         # literals like this '\037\213'. xgettext thinks it has to
         # parse them even though they are not marked for translation.
         # Extracting with an explicit encoding of ISO-8859-1 will make
         # xgettext "parse" and ignore them.
 	echo $(PYTHON_FILES) | xargs \
 	  xgettext --package-name "Mercurial" \
 	  --msgid-bugs-address "<[e-mail]>" \
 	  --copyright-holder "Matt Mackall <[e-mail]> and others" \
 	  --from-code ISO-8859-1 --join --sort-by-file \
 	  -d hg -p i18n -o hg.pot
 
 %.po: i18n/hg.pot
 	msgmerge --no-location --update $@ $^
 
 .PHONY: help all local build doc clean install install-bin install-doc \
 	install-home install-home-bin install-home-doc dist dist-notests tests \
 	update-pot